Which Statement About Soapberry Bug Beaks Is True

Which statement about soapberry bug beaks is true?

A) Beak length is not a heritable trait.
B) Beak length has evolved in response to changes in the feeding habits of the soapberry bugs.
C) Measurable changes in average beak length have occurred on a time scale of centuries, but are not detectable on a time scale of a few decades.
D) Soapberry bugs feed on the same plant host species everywhere they occur, which is what makes it possible to study the evolution of beak length across their geographic range.