How can regular physical activity benefit the health of the heart? A. It will keep the heart from working too hard.

B. It avoids putting disease causing chemicals in the body.

C. It will help to keep blood pressure within range.

D. It will strengthen the heart muscle.

Which of the following statements concerning cancer and mutations is correct? a: cancer can only occur with a mutation in a somatic cell. b: usually, multiple mutations are required in different genes to cause cancer. c: none of the other answer options is correct. d: cancer can only occur with a mutation in a germ cell. e: usually, a single mutation is all that is required to cause cancer.