The folktale that claims that a rattlesnake's age can be determined

It would be very easy to mark Options A & D if one doesn't understand the passage properly.

The Passage has an annoying structure. It has two derived statements.
The author wants you to believe two things.
1) That the folktale's claim is flase. (Counting the sections of rattle can help judge a snake's age)
2) That this claim could be true if a particular scenario doesn't exist. (That the rattles are brittle)

Clearly, the 2nd statement is the main conclusion.
A scenario that inhibits or causes this method (Counting) to fail would break the conclusion. Thus, ruling out such a scenario would be an assumption.
Examples of such scenarios -
A. Rattles are lost each time the snake molts.
B. Molt process unusually takes place due to determinant factors (Environment,
Climate, etc.
The right Answer choice E rules out scenario B with the availability of food becoming the factor.
Choice C might seem like a trap choice to some, but snakes molting more frequently when young is more of a fact which can be foreseen and can be taken into consideration while calculating the age of the snake.

Can you plz help me that Why Option E is correct?

I mean what's the connection with food here?

The folktale that claims that a rattlesnake's age can be determined from the number of sections in its rattle is false, but only because the rattles are brittle and sometimes partially or completely break off. So if they were not so brittle, one could reliably determine a rattlesnake's age simply from the number of sections in its rattle, because one new section is formed each time a rattlesnake molts.

Which one of the following is an assumption the argument requires in order for its conclusion to properly drawn?

(A) Rattlesnakes molt exactly once a year

(B) The rattles of rattlesnakes of different species are identical in appearance

(C) Rattlesnakes molt more frequently when young than when old

(D) The brittleness of a rattlesnake's rattle is not correlated with the length of the rattlesnake's life

(E) Rattlesnakes molt as often when food is scare as they do when food is plentiful

This question breaks the myth apart that external information is required in question that seek to either strengthen or weaken the argument.
It was between D and E for me, unfortunately it was D for me.
No only i got confused by D but E had this food info that seemed to make no sense. Had the part " as they do when food is plentiful" not been there it would been easier for me to choose it over D. However, now i realise that If there's molting variability wrt to food the proportionality to calculate age fails to stand, breaking the argument.
In D, even if its related the calculation of age is still holds because its known that how age affects brittleness. But i would still not give it a thumbs up or down simply for the reason that it's still confusing. E, on the other hand is clear.

Answer E.

GMATNinja GMATNinjaTwo Can you help with this Question?­

 

­You're in luck: we covered this question in a YouTube video. Check out the 3rd question in this video for a full explanation.Enjoy, and let us know if that doesn't help!

Classic example of a "Assumption PREVENT FROM WEKNESS" type assumption questions.

conclusion: Brittle is the reason which prevents age counting.

Option E) says Snake molts at the same rate, even if food is scare or plentiful. (I read this wrong and marked B)
It protects from weakness of the conclusion and says "food is not the reason"