Read the following passage and mark the lett...

Câu hỏi: Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the following questions from (46)to (55)

A. To indicate that more research is needed in this field.

B. To contradict the idea that animals can count

C. To show how attitudes have changed since1786

D. To provide evidence that some birds are aware of quantities.