Which of the Following Reflect Internal Changes Due to Aging

Multiple Choice

Which of the following reflect internal changes due to aging?

A) The heart's capacity to pump blood through the circulatory system to the brain is reduced and impeded by hardening and shrinking of blood vessels.
B) The reduction in gray matter makes the aging brain less efficient.
C) The respiratory system is unchanged unless the person was exposed to cigarette smoke.
D) The digestive system becomes less efficient at drawing nutrients from food, leading to frequent diarrhea.