You will hear five persons talking about different things. Decide the subject of their talk by the speaker. Write one letter(

It showed a population of 1，008，175，288，or one-quarter of the human race．There was a nineteen-point questionnaire to complete，and with the help of twenty-nine computers the information was broken into categories such as age，occupation and marital status．

The morning starts with a jog through the forest followed by a freezing cold shower．Then comes a frugal breakfast．After breakfast there are lectures on all sorts of health subjects，such as smoking，overeating，and maintaining a balanced diet．