According to the passage, which people seem to age slower than the others

A．something to be considered
B．branch of knowledge studied
C．persons chosen to be studied in an experiment
D．any member of a state except the supreme ruler

A．our brains shrink as we grow older
B．sixty-year-olds have better brains than thirty-year-olds
C．the front section of the brain does not shrink
D．some people's brains have contracted more than other people's