Penguins, seals, and tuna have body forms that permit rapid swimming, because
A) all share a common ancestor at some point in the past.
B) this is the only shape that will allow them to maintain a constant body temperature in water.
C) flying, pregnancy, and gill-breathing all require similar adaptations in form.
D) the shape is a convergent evolutionary solution to the need to reduce drag while swimming.
E) all of their bodies have been compressed since birth by intensive underwater pressures.
Answer: D