This is an Evaluate/Assess question type. An 'Evaluate the Argument' question basically asks us the question 'what is missing in the argument before the argument can be deemed complete?'. In other words, we are looking for the missing premise to complete the conclusion. In an evaluate question, the options would be presented in a question format, and we are concerned with identifying the answers at either ends of the spectrum. For example, in a question beginning 'whether', the two applicable answers are 'Yes' and 'No'. Similarly, in a question beginning with 'When', we consider two extreme answer choices - say, 2 minutes OR 2 years. If one answer choice (or one end of the spectrum) strengthens the argument, the other end should weaken. Therefore, a good way to approach an 'Evaluate' question is to treat it solely as either a Strengthen or a Weaken question type, based on whichever your strong suit is.

Coming back to the question, let us dissect the argument into its premises and conclusion.

Premise 1: A liquid released by pinkback ants contains chemicals that can be used to treat minor flesh wounds
Premise 2: The liquid is stored in the ants' glands in very small quantities

Conclusion: It will be very expensive - i.e., take a long time - to collect sufficient quantities of this chemical for treatment of flesh wounds.

Let us approach this as a Weaken question, and say that it will not be very expensive to acquire sufficiently large quantities of this chemical to treat flesh wounds. We are looking for an option that, when answered either way, does this for us.

Option A - INCORRECT: We are not concerned with various commercial applications - only with treatment of flesh wounds. Irrelevant and out of scope
Option B - INCORRECT: Again, this is out of scope. Treatment other than flesh wounds is beyond the domain of the argument - we are only concerned with flesh wounds
Option C - INCORRECT: Irrespective of whether it takes 5 minutes or 5 years, the point is that the ants can store only a very small amount in their glands at a given time. So, it will still be expensive to collect the liquid in large enough quantities.
Option D - INCORRECT: Out of scope
Option E - CORRECT: This is what we are looking for - If the compound can be produced synthetically or artificially, then we can just obtain the chemical in small quantity from the ants' glands and produce large volumes of it relatively inexpensively. So, a 'Yes' answer to this question weakens the argument. Alternatively, if the chemical cannot be produced artificially, and the ants only store a small amount of the liquid chemical in their glands, then we have no choice but to gather the chemical naturally, which would take a lot of time and resources and be expensive. Hence a 'No' answer strengthens the argument.

Option E, therefore, is the best answer.

Please let me know if anything doesn't make sense.