Final answer:
Cancer patients, transplant patients, and AIDS patients are more susceptible to frequent viral infections due to compromised immune systems.
Step-by-step explanation:
Option 1: Cancer patients, especially those with leukemia or lymphoma, are more susceptible to frequent viral infections due to compromised immune systems. Cancer itself weakens the immune system, and treatments such as chemotherapy or radiation therapy can further suppress the immune response, making patients more vulnerable to viral infections.
Option 2: Transplant patients are also at a higher risk of viral infections due to compromised immune systems. To prevent organ rejection, transplant patients are often given immunosuppressive medications that suppress the immune system, making them more susceptible to viral infections.
Option 3: Acquired Immunodeficiency Syndrome (AIDS) patients have severely compromised immune systems, as the disease attacks their immune system. This makes them highly susceptible to viral infections and opportunistic diseases, which can be life-threatening.