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 long...

A. I think keeping fit is necessary for everyone.

B. As far as I know, more and more people exercise to keep fit.

C. Fitness centres are mushrooming.

D. I just do morning exercise and maintain a balanced diet.

A. Why do they need to keep fit?

B. It's very important for old-aged people to have a healthy lifestyle.

C. I do think so. As the main labour force of the country, they must be strong.

D. It doesn't cost much to work out in the gym these days.