Researchers briefly anesthetized chimpanzees and painted an odorless red dye on their heads. When they awoke and looked in the mirror, the chimps immediately reached to touch their brows and ears where the dye was. These findings suggest that chimps __________.

a. develop a sense of self-recognition comparable to that of two-year-old humans.

b. have a complex, multifaceted sense of self.

c. are capable of developing a sense of self-esteem.

d. possess a self-concept much like an adult human's.