单项选择题
A．How can I do that B．Are you going today C．Did you get it D．Do you have that E．Would you like my help F．Yes，I know G．NO，I don’t know H．Can I sell my used books
A. how people’s brains shrink B. the way of making people live longer C. the size of certain people’s brains D. why certain people aged sooner than others