Definition: You are given a question on medical genetics. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: Mutations that cause achondroplasia exert an effect which can be classified as:
(A)dominant negative. (B)gain-of-function. (C)haploinsufficiency. (D)loss-of-function.

B