题目内容：

A new study finds that young females in one group of African chimps(黑猩猩) use sticks as dolls more than their male peers (同龄) do, often treating pieces of wood like a mother chimp caring for a baby. In human cultures around the world, girls play with dolls and pretend that the toys are babies far more than boys do.

Chimp observations, collected over 14 years of field work with the Kanyawara chimp community in Kibale National Park in Ugandan, provide the first evidence of a nonhuman animal in the wild that exhibits sex differences in how it plays. This finding supports an argument that biology as well as society underlies boys’ and girls’ different toy preferences.

Stick play occurred most commonly between ages 3 and 9. Females spent a lot more time carrying sticks than males did. Young male chimps occasionally used sticks to mimic(模仿) childcare. “Far more often, they fought with sticks, an infrequent behavior among females,” say Sonya Kahlenberg of Bates College in Lewiston, Maine, and Richard Wrangham of Harvard University.

“Biological differences between the sexes make female chimps more receptive to stick-mothering than males,” says Wrangham.

Consistent with reported cultural traditions among adult chimps, Kanyawara youngsters learned from each other to play with sticks as if caring for babies. Stick play among young chimps showed no evidence of being directly influenced by older chimps. Child-bearing females never played with sticks and thus didn’t model such behavior for younger chimps.

Young females carried sticks for anywhere from a few minutes to several hours. They often rested in nests with their sticks, sometimes playing with them much as chimp mothers play with their babies though they didn’t get any form of teaching from the adults.

1.What does a stick seem like to a young female chimp who plays with it?

A. A doll.    B. A mother.    C. A baby.    D. A toy.

2.We can see from the text that young female chimps ________.

A. often carry sticks with males

B. always carry sticks with males

C. never use sticks in fighting

D. seldom use sticks in fighting

3.From whom do the young chimps pick up the stick play behavior?

A. From each other.    B. From older chimps.

C. From their mothers.    D. From male chimps.

4.What does the text mainly tell us about young chimps’ stick play?

A. The types of stick play and social influence.

B. The sex differences and social influence.

C. The sex differences and age differences.

D. The ways of stick play and age differences.