In individuals with normal immune function, the likelihood of developing malignant tumors is low. However, in people with weakened or deficient immunity due to AIDS, the probability of developing malignant tumors significantly increases. This indicates the presence of which of the following functions of the immune system?
Correct answer: C. cancer surveillance
The question highlights the role of the immune system in preventing malignant tumors. In individuals with normal immunity, the immune system can effectively monitor and eliminate potential cancer cells, which is known as cancer surveillance.