The correct answer is option 1, which states that antibiotics are only useful for bacterial infections. Antibiotics are medications that are designed to kill or inhibit the growth of bacteria in the body. They work by targeting specific components or processes within bacterial cells that are essential for their survival. This includes blocking the synthesis of bacterial cell walls or disrupting vital metabolic pathways. However, antibiotics are not effective against viral infections. Viruses are different from bacteria as they cannot be killed by antibiotics since they are not living organisms. Viral infections typically resolve on their own over time as the immune system fights off the infection. In summary, antibiotics are specifically designed to combat bacterial infections and are not effective in treating viral infections.