The Similar Fusiform Body Shape of Diverse Animals, Such as Sharks

The similar fusiform body shape of diverse animals, such as sharks, penguins, and aquatic mammals, has evolved because

A) natural selection typically has no limits when different organisms face the same challenge.
B) respiration through gills is enhanced by having a fusiform shape.
C) this is the body shape that makes it possible for aquatic animals to swim rapidly.
D) the fusiform shape is coded by the same genes in all three types of aquatic animals.
E) all three types evolved from the same ancestral form, which flew in air rather than swam in water.