Answer:
C. value
Explanation:
It isn't any of the other three, and opinion isn't an option. The speaker believes the value of voting lies in the result of better leaders.
The analogy is meant to show parallels between two sets of words. Fertile is to arable as vague is to clouded. If you understand either pair it can be used to decipher the meaning of the other pair you don't know.
The number of letters in the word