A certain species of desert lizard digs tunnels in which to lay its eg

There is competition for real estate among lizards as there is relatively small area which they prefer to dig to lay eggs.
This competition is usually high during egg laying season.
Hence eggs are at high chances of being disturbed during this egg laying season as another lizard may accidentally dig up the same space which was used by other lizard.
Once this season is over , eggs are usually not disturbed.
So it makes sense to guard eggs until the egg laying season is over.

IMO answer A .

we need some answer which states that it is unnecessary to guard after few days. A gives exactly what we wanted. Hence, I choose A

Target gmat against the odds.

can anyone plz explain C.

(C) Each female lizard lays from 15 to 20 eggs, only about 10 of which hatch even if the eggs are not disturbed at any time during the incubation period.

Isn't it telling that there is no connection of disturbance to the hatching capabilities.

The main point here is that the lizard needs to guard its tunnel for only a few days after laying its eggs, so we need an answer choice that lends credibility to this statement. Option C says that out of 15/20 eggs that the lizard lays only 10 hatch and we tend to assume that these 10 eggs will take a few days to hatch. Now how can we make that assumption, how do we know that 10 eggs will take a few days or many days to hatch. If 10 eggs were to take a few days to hatch then this indeed gives a reason as to why lizard guards its tunnel for only a few days but if these 10 eggs take many days to hatch then isn't the lizard expected to guard its tunnel for those many days.

A certain species of desert lizard digs tunnels in which to lay its eggs. The eggs must must incubate inside the tunnel for several weeks before hatching, and they fail to hatch if they are disturbed at any time during this incubation period. Yet these lizard guard their tunnels for only a few days after laying their eggs.[/quote]

Which of the following, if true, most helps explain why there is no need for lizards to guard their tunnels for more than a few days?

(A) The eggs are at risk of being disturbed only during the brief egg-laying season when many lizards are digging in a relatively small area.

(B) The length of the incubation period varies somewhat from one tunnel to another.

(C) Each female lizard lays from 15 to 20 eggs, only about 10 of which hatch even if the eggs are not disturbed at any time during the incubation period.

(D) The temperature and humidity within the tunnels will not be suitable for the incubating eggs unless the tunnels are plugged with sand immediately after the eggs are laid.

(E) The only way to disturb the eggs of this lizard species is by opening up one of the tunnels in which they are laid.

I marked (D) , but after reading the explanations it is clear that (A) is better than (D).

B, C, and E are Irrelevant.

Step 1:- Read the question stem:- Which of the following, if true, most helps explain why there is no need for lizards to guard their tunnels for more than a few days?-----> identify the gap in logic!!

Step 2: Analyze the stimulus:-
1) A certain species of desert lizard digs tunnels in which to lay its eggs. ----> Lizards dig - tunnels - lay eggs
2) The eggs must incubate inside the tunnel for several weeks before hatching, -----> incubation period
3) and they fail to hatch if they are disturbed at any time during this incubation period. ------> don't disturb during incubation period
4) Yet these lizard guard their tunnels for only a few days after laying their eggs. -------> lizards don't guard for the entire length of incubation period

Step 2B: Read the question stem once again so that you can analyze in a better way. [Thanks jennpt -inserted this step after your feedback ]

Step 3: Analyze options, eliminate wrong ones and select the right one:-
Option (A) The eggs are at risk of being disturbed only during the brief egg-laying season when many lizards are digging in a relatively small area.---->tries to explain but is sounding slightly vague...read on!!

(B) The length of the incubation period varies somewhat from one tunnel to another.---->out of scope

Option (C) Each female lizard lays from 15 to 20 eggs, only about 10 of which hatch even if the eggs are not disturbed at any time during the incubation period.----> even if the eggs are not disturbed only 10 out of 15/20 hatch. But what if the tunnel is disturbed? why doesn't the female lizard safegaurd for the entire length of incubation duration?

(D) The temperature and humidity within the tunnels will not be suitable for the incubating eggs unless the tunnels are plugged with sand immediately after the eggs are laid.------>out of scope, does not explain why the female lizard leave early?

(E) The only way to disturb the eggs of this lizard species is by opening up one of the tunnels in which they are laid. .------>out of scope, does not explain why the female lizard leave early?

So we are down to A vs C, lets look more closely:-

Option (A) The eggs are at risk of being disturbed only during the brief egg-laying season when many lizards are digging in a relatively small area.----> makes much more sense now---you get the point---->notice the choice of words, "brief egg-laying season" -----> means many females get together to lays eggs. They dig the tunnels together. Some female lizards might dig early and some others might take more time. The ones who finish digging their tunnels early; enter the tunnel & lay their eggs but when they come outside they find some female lizards are still digging tunnels. They realize that these might cause disturbance to the eggs which they have themselves laid. They wait for all the females to finish digging their tunnels. Once everyone is done, they might leave early and not wait for the entire length of incubation period!! -----> BINGO---> makes much more sense now!!

Step 4:- Choose the correct answer choice!!
The problem with option (C) still remains...hence we can choose (A) over (C)---->Which happens to be the right answer


jennpt - please consider reviewing or providing feedback!! Your comments are invaluable!!

that is when they make their best to protect their eggs , only a certain percent of eggs will succeed . The fail of the rest of the eggs is not in the lizards' control . That "natural "rule will happen with or without protection .
But if lizards don't make their best , a lower percent will succeed , because now they are facing tow negative factors : the natural law AND the disturbance .
so there is a connection between disturbance and hatching .

Hi jennpt

Thanks for taking the time out amidst your busy schedule and giving me your feedback.

Your explanations/examples are very nice & feedback is really very helpful.

I have made a note of your points and I will insert step 2B in my approach to such questions.

I like your metaphor of "clear shopping list" but sometimes the GMAT answer choice are so confusing. I am able to do well on easier CR questions but unable to imagine my "shopping list" on tougher questions. I don't know how you could manage a V51...kudos to you...I am super impressed with you

Thanks once again!!

"The eggs must must incubate inside the tunnel for several weeks before hatching, and they fail to hatch if they are disturbed at any time during this incubation period "

A) The eggs are at risk of being disturbed only during the brief egg-laying season ( Doesn't it contradict with the above? ). Also what does the season means? What would be it in comparison to days or weeks?

Pardon me for this as it is really confusing for me.

I would like to add to two other famous choices - options C and D - as to why they are incorrect in my view:
"D gives a possibility that the incubation itself may cause harms and laying SANDS is NECESSARY for the proper incubation. Now there could have been a possible link, if we were given that these LIZARDS don't guard it but also plug it with sand and then it's good. That might have explained, but we do not know whether they would plug or not"

Option C says that only 10 out 15 to 20 eggs hatch even if not disturbed in the given incubation period.
Now when choosing option C, people might think that well, the success rate is near 50-60% but not 100% so, the lizards might not care, but from the given argument, we don't know whether they care or not. What if this success rate is all lizards want? And if they want this why do they not continue and leave? We don't know that. Even option C had said that 50-60% success rate of hatching is favorable for these lizards, still it would not have led us to resolve our paradox."

Regards,
Rishav

but isn't it trying to make us stick to the assumption that guarding can prevent disturbance in default? eg. noise can be disturbing as well even with the guarding.

"A certain species of desert lizard digs tunnels in which to lay its eggs."
I have seen such a sentence construction for the first time. DmitryFarber or GMATNinja or mikemcgarry or other verbal experts could you please throw some light on such a sentence construction.

A certain species of desert lizard digs tunnels in which to lay its eggs.

Meaning : Lizard digs tunnels . It lays eggs into tunnel.

A certain species of desert lizard digs tunnels in which to lay its eggs.


in which to lay its eggs.: prepositional phrase adding information about tunnels.
which - pronoun refer to tunnels
its: refer to lizard

Thank you so much for the clarification.

When many lizards are engaged in digging their tunnel that time the eggs might be disturbed. If the digging time is not that much longer the chance of disturbance minimalized. So the lizards do not guard their tunnels for along time.
The answer is A.

Hi AndrewN avigutman - i thought (A) was wrong because of the following reason



Lets say :

• the egg-laying season is the month of March for all lizards. Some lizzards lay in week 1 | some lay in week 2 | some lay in week 3 | some lay in week 4.
• Incubation period after you lay eggs eggs - 8 weeks.

With that thinking, I looked at the red specifically and marked (A) wrong. Reason -

To me, the words in the red --- reinforced the thinking that mother lizards SHOULD be around their tunnel for the entire month of March when lizzards come to lay their eggs

Why ? Beacuse every lizard is digging in a relatively small area. in order to lay their eggs.

So , if i am the mother lizard, I need to be around my tunnel for the entire month of March

Why ? To ensure, no other female lizard burrows and digs close enough to my tunnel that causes disturbance to my eggs (As my eggs are incubating)

^^^ Contd. from above AndrewN avigutman -- Example



Thus, option (A) goes the other way and re-inforces why every mother lizard, needs to be around her own tunnel for the entire month of March (Till every other lizzard lays her eggs)

(A) did not explain why a mother lizards leaves after a couple of days.