Consider statements about human immunity: 1. B-lymphocytes produce antibodies. 2. T-lymphocytes are involved in cell-mediated immunity. 3. Vaccines cure active viral infections. Which are correct? MCQ with Answer and Explanation

B-lymphocytes (B cells) differentiate into plasma cells that secrete antibodies, providing humoral immunity. T-lymphocytes (T cells) are responsible for cell-mediated immunity, directly attacking infected or cancerous cells. Vaccines are prophylactic; they stimulate the immune system to develop memory and prevent future infections, but they do not cure active, ongoing viral infections. Thus, statements 1 and 2 are correct.