Each of the Following Observations Supports the Hypothesis of "Immune

Each of the following observations supports the hypothesis of "immune surveillance" or constant activity by the immune system to detect and destroy abnormal tissues and tumors except

A) The incidence of tumors in humans is highest when the immune system is not functioning optimally (young children and the elderly) .
B) Many tumors are infiltrated by lymphocytes, and spontaneous remission of tumors has been observed.
C) Tumors caused by viruses occur more frequently in immunocompromised patients.
D) The incidence of clinically undetectable tumors in human autopsies is higher than would be expected from actual rates of cancer in particular populations.