Antibiotics target bacterial infections only Steps:

• Identify that antibiotics kill or inhibit bacteria but are ineffective against viruses or other pathogens.
• Assume standard examples: 1 is bacterial (e.g., typhoid), 2 is viral (e.g., common cold), 3 is viral (e.g., AIDS).
• Determine which cannot be treated: viral diseases 2 and 3 resist antibiotics.
• Match to option D, excluding bacterial disease 1.

Why D is correct:

• Antibiotics work via bactericidal or bacteriostatic mechanisms, per microbiology definition, ineffective on viruses lacking bacterial cell walls.

Why the others are wrong:

• A includes 1, a bacterial disease treatable by antibiotics.
• B includes 1, incorrectly grouping a treatable bacterial disease.
• C includes 1, wrongly pairing it with only one viral disease.

Final answer: D