Parasitic Species Tend to Have Simple Morphologies

Multiple Choice

Parasitic species tend to have simple morphologies. Which of the following statements best explains this observation?

A) Parasites are lower organisms, and this is why they have simple morphologies.
B) Simple morphologies have been naturally selected for in most parasites.
C) Parasites have not yet had time to progress, because they are young evolutionarily.
D) Parasites do not live long enough to inherit acquired characteristics.