I'd go with C. what's the OA?

IMO D as

If the survey is not on a broad spectrum of people, than it conclusion can be biased. Also it can not stand the negation test.

the question states:
taste = sight + smell + (others)
others is important because it says " taste buds are not the only sensory organs involved". so there is something else involved too. who knows maybe touch (skin),etc
what is the implicit assumption made above? Lets look at the answers and eliminate few:
B is incorrrect
C is also incorrect (since it doesnt consider anything beyond sight and smell)
D - out of context
thus, we are left with A and E
E merely imitiates the same set of experiment with different attributes. there is no implicit assumption that can be derived out of it. (or could you?)
A - The experiment is conducted to evaluate different factors in determining the taste of objects. In context of the question, fundamentally they should have different taste to derive a conclusion. Thus, A must be the correct answer!

Correct Answer: C

Explanation: This argument concludes that taste buds are not the only sense organs involved in determining the taste of a piece of food. This assumes that "taste" can be defined as something more than the function of the taste buds alone. If taste could not be used to describe an experience that involved sight or smell -- in other words, if taste was simply what the taste buds do, regardless of whatever else is happening, then the conclusion would be flawed. However, choice C, which strengthens the conclusion, allows "taste" to have a definition that includes the use of other senses. Choice A is incorrect because there is no need for complete agreement that an apple and an onion differ in taste. Choice B is incorrect because additional senses besides the ones mentioned in the argument are not relevant. Answer D implies that the research was well done, but this alone does not make the conclusion any more valid. Choice E actually weakens the conclusion by suggesting that taste buds alone can be used to differentiate some foods.

I am still not convinced. Can a expert please help us to get this clear? Kasia please help!