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

A．why certain people are aging sooner than others
B．how to make people live longer
C．the size of certain people's brains
D．which people are most intelligent

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