Which of the following is a question of value?
a. “what are the causes of autism ”
b. “is human cloning ethical ”
c. “how does a car engine work ”
d. “should the drinking age be changed ”

The first question is about a specific cause, so it's not about value. The second question is just about value, since the value of an action is being re-examined, which can affect ethics. The third question relates to the functioning of the mechanism. The fourth question relates to an action that, if it happened, would surely have value, but indirectly, if that happens, there is no direct question about the value as in the second question.

The answer is: b.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

it should be d or b but i'm sure it's d