The correct option is C When HIV replicates rapidly in T helper cells and damage large number of these.
Once the HIV enters the human body, it takes years for it to capture the immune system of the body. In the stage of active replication, there is a progressive decrease in the number of T helper cells in the body, and the person suffers from bouts of fever, diarrhoea and weight loss. They also suffer from infections that could have been otherwise evaded easily, such as those due to pathogens like mycobacteria, viruses and fungi. This is mainly because the action of T killer cells which are dependent on T helper cells, gets inhibited. Normally, the signals activating the T killer cells are sent by the T helper cells on identifying a foreign particle entering the body, thereby alerting the T killer cells to destroy the infected cells.