Mark the letter A, B, C, or D to indicate the correct response to each of the following exchanges. Two friends Nam and Lan are talking about the topic of healthy lifestyle and longevity.

Question. Lan: What do people do to keep fit? - Nam: ____

A. Everyone wants to keep fit these days.

B. So many people do harm to their health by smoking or drinking.

C. They combine exercising and having a balanced diet.

D. Not many people can afford to eat healthily.