Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.
There is an important difference between humans and apes. Apes walk on four legs.
A. Apes walk on four legs, so they are importantly different from humans.
B. There is an important difference between humans and apes that walk on four legs.
C. There are important differences between humans and apes that walk on four legs.
D. An important difference between humans and apes is that apes walk on four legs.
