Of all the sports shoes, John bought _____ pair. Then he had some money for socks. [ ]

A. a cheaper

B. the most wonderful

C. the least expensive

D. an expensive

The main reason for the fast growth of population is not()a rise in birth rates as a fall in death rates as a result of improvements in public health service and medical care.

A. such

B. the same

C. so much

D. as much