The introduction of ladybugs into a garden ecosystem is an excellent

Question

The introduction of ladybugs into a garden ecosystem is an excellent method of protecting ornamental flowers from aphids. Unfortunately, the ladybugs will only prey on the aphids for a week before flying away, and no aphid infestation severe enough to warrant the deployment of ladybugs can be cleared in a single week. However, although synthetic pesticides are not much longer lasting, they can be easily reapplied whenever the aphids reappear. Clearly, therefore, for protecting ornamental flowers from aphids, introducing ladybugs can play no useful role.

The argument is most vulnerable to the objection that it fails to

A. consider that there might be less severe aphid infestations that can be cleared in a week
B. allow for the possibility of combining the two aphid-control methods it mentions
C. distinguish among the several varieties of synthetic pesticides
D. mention any alternative aphid control method that could be utilized in place of the rejected method
E. allow for the possibility that the introduction of insects other than ladybugs might have the same effect.

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vasu1104 · Answer

ladybug is good way ton protect ornamental flowers from aphids. 
 but ladybug only prey on aphid for week before they fly. 
 not possible to clear the large aphids infestation by ladybugs in week. 
 synthetic pest can be used but they are no much longer lasting.

Conclusion= ladybug can play no useful role in protecting ornamental flowers.

it basically says that ladybug can be there for only week and they cant get rid of large aphid and pesticides are not effective, ladybug cant protect the flowers. 
 A we know from passage that they are somewhat effective in week 1. so this choice doesnt tell why conclusion is wrong or blindsided. 
 B this make sense. if ladybug does some lifting in week 1 and then introduced the pesticide, we can certainly remove aphids. so ladybug did its job. its just we need to combine two methods to get the results which author failed to look here. Perfect Weakener here. 
 C no variety of synthetic pesticides have been mentioned. 
 D we are concerned about ladybug not being right one. no interested with other alternative here. 
 E out of context.

Dereno · Answer

In a garden ecosystem, in order to protect the ornamental flowers within the garden ecosystem, lady bugs are introduced to prey on the aphids, that feeds on the ornamental plants.

But, lady bugs feed on the aphids for one week only. After that the lady bugs fly away. So, the lady bug cannot kill all the aphids in the limited span of a week.

Thus, post one week, synthetic pesticides can be applied , when the aphids reappear. So that the ornamental plants are free from aphids infestations.

The final conclusion made by the author is :

For protecting ornamental plants from aphids infestation, the ladybug plays no useful part.

We need to find a weakener:

A. consider that there might be less severe aphid infestations that can be cleared in a week.

If in a week, ladybugs have cleared a less severe aphid infestation. Then, the conclusion mentioning lady bugs played no useful part falls apart. But, wait are we rushing. Yes - might be cleared, this throws a bit of doubt whether it can happen or not.

Secondly, within one week does the pesticides do it role or does the lady bug did its part. We are not sure of.

Moreover, the author is stressing on infestations which cannot be treated within a week. But, this option mentions about infestations which are eradicated within a week.

Hence, Wrong.

B. allow for the possibility of combining the two aphid-control methods it mentions.

If we combine the two aphid control methods, we can be sure of the impact ladybugs have created on the aphids population and the extent synthetic pesticides was used to treat aphids. This can be effective is ascertaining the role of ladybugs. Hence, a weakener.

C. distinguish among the several varieties of synthetic pesticides.

This option is completely out of scope, as it does a marketing role promoting the different types of pesticides in the market. The bone of contention is between lady bugs (week 1) vs synthetic pesticides (after week 1). Hence, wrong.

D. mention any alternative aphid control method that could be utilized in place of the rejected method.

This brings a new perspective to the solution, and demands to be weighed against the current two alternatives. Irrelevant to the context. Hence, Wrong.

E. allow for the possibility that the introduction of insects other than ladybugs might have the same effect.

This is also a severe distractor and irrelevant option. Hence, Wrong.

Option B

Sajjad1994 · Answer

Explanation

-Ladybugs prey on aphids for only a week.
-No aphid infestation severe enough to warrant ladybugs can be cleared in a week.
-Synthetic pesticides don’t last much longer but can be reapplied easily when aphids return.

Conclusion:  Therefore, introducing ladybugs can play no useful role in protecting ornamental flowers from aphids.

The key leap here: just because severe infestations can’t be cleared in a week, that doesn’t necessarily mean ladybugs have no useful role. The author assumes that the only use for ladybugs is to fully clear a severe infestation in one go. But maybe: They can help with less severe infestations (but the argument explicitly restricts reasoning to  “infestations severe enough to warrant ladybugs”  so maybe that’s defined as severe only).

A.  Less severe infestations: The argument says  “no aphid infestation severe enough to warrant the deployment of ladybugs can be cleared in a week”  that doesn’t rule out that ladybugs might be deployed for less severe infestations, but if the argument defines their use as only for severe cases, maybe that’s consistent. Still, maybe ladybugs are useful even in severe cases as part of control. This is possible, but maybe not the strongest objection.

B.  Combining the two methods: This seems strong. The argument compares ladybugs alone (ineffective for severe infestations because gone in a week) vs. pesticides alone (can be reapplied). It doesn’t consider that ladybugs could be part of an integrated pest management for example ladybugs reduce population, pesticides mop up rest. So it fails to allow for the possibility of combining them, which would give ladybugs a useful role.

C.  Distinguish varieties of synthetic pesticides: Irrelevant to ladybugs’ usefulness.

D.  Mention alternative methods: The conclusion is about ladybugs playing no useful role; we don’t need to mention alternatives to object to the reasoning.

E.  Other insects having same effect: That wouldn’t show ladybugs have a useful role, just substitutes.

Answer: B

laborumplaceat · Answer

B is correct. This is one of the typical kind of questions in which there are 2 methods to solve a certain problem and 1 is rejected due to a reason which is along the lines - that that method will not be sufficient to solve the problem. These kind of arguments are most vulnerable to the objection that they do not include the possibility of using both the methods instead of just one of them.
A is incorrect as it is given in the passage that "no aphid infestation severe enough to warrant the deployment of ladybugs can be cleared in a single week"

ExpertsGlobal5 · Answer

Video explanation:

https://www.youtube.com/watch?v=Dq2zIxLW2EU

The introduction of ladybugs into a garden ecosystem is an excellent

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