Why does the author mention 4,500 years? 

Câu hỏi:  Why does the author mention 4,500 years? 

A. To note that the Great Pyramid is the oldest wonder. 

B. To show that the Great Pyramid is very young

C. To prove that the Great Pyramid is the strongest structure in the world. 

D. To explain why so many workers worked on the Great Pyramid.