Marcus is able to achieve an erection by either masturbation or manual stimulation by his partner. He has no difficulty ejaculating when he masturbates, but he cannot ejaculate during intercourse. Marcus would likely be diagnosed with?

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.