(A) Repent - feel or express sincere regret or remorse about one's wrongdoing or sin.
(B) Make thin - to reduce something
(C) Force -coercion or compulsion, especially with the use or threat of violence.
(D) Divide - separate or be separated into parts.
The given word Attenuate means to reduce the force, effect, or value of. From the explained meanings we can clearly see that option (B) fits the description of the given word. Hence the answer is option (B).
Option (A) and (C) are unrelated. Option (D) means to reduce to smaller parts and not just the action of reduction which is indicated by the given word.