Consider statements about human immunity: 1. Skin acts as a physical barrier. 2. White blood cells fight infections. 3. Antibiotics are effective against viruses. Which are correct? MCQ with Answer and Explanation

The skin and mucous membranes form the first line of defense (innate immunity), acting as physical barriers that prevent pathogens from entering the body. White blood cells (leukocytes), including phagocytes and lymphocytes, are the cellular components of the immune system that identify, attack, and destroy pathogens. Antibiotics are drugs designed to kill or inhibit the growth of bacteria; they are completely ineffective against viruses, which lack the cellular machinery targeted by antibiotics. Thus, statements 1 and 2 are correct.