Many important types of medicine have been developed from substances discovered in plants that grow only in tropical ...

John on July 22, 2016

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Please explain why A is correct rather than the other options

1 Reply

Mehran on August 7, 2016

@texasjohnrh let's break the stimulus down first.

The conclusion here is, "Thus, if the tropical rain forests are not preserved, important types of medicine will never be developed."

The support for this conclusion?

"Many important types of medicine have been developed from substances discovered in plants that grow only in tropical rain forests."

"There are thousands of plant species in these rain forests that have not yet been studied by scientists, and it is very likely that many such plants also contain substances of medicinal value."

This is a Strengthen with Necessary Premise question, so we are looking for the answer choice that not only strengthens the argument but that is also necessary to the argument.

(A) states, "There are substances of medicinal value contained in the tropical rain forest plants not yet studied by scientists that differ from those substances already discovered in tropical rain forest plants."

This clearly strengthens the argument because if (A) is true and these plants only grow in tropical rain forests, then clearly important types of medicine will never be developed if these tropical rain forests are not preserved.

Now let's negate (A) to make sure that it is also necessary to the conclusion here.

The negation of (A) is, "There are NOT substances of medicinal value contained in tropical rain forest plants not yet studied by scientists that differ from those substances already discovered in tropical rain forest plants."

The negation of (A) destroys the argument because if there are not substances of medicinal value that differ from those substances already discovered in tropical rain forest plants, then it would not be true that "important types of medicine will never be developed" if the tropical rain forests are not preserved.

So (A) would be the correct answer.

Hope this helps! Please let us know if you have any other questions.