Which of the Following Is Not a Reason Why Trade-Offs

Which of the following is not a reason why trade-offs constrain evolution?

A) Most adaptations impose both fitness costs and benefits.
B) Structures such a horns and antlers are metabolically costly to produce, but result in more reproduction by the males that possess them.
C) Changes in allele frequencies may be influenced by chance events.
D) Ability to consume toxic prey may reduce mobility.
E) Adaptations can evolve only if the fitness benefits they confer exceed the costs they impose.