Selective Pressure from Antibiotic Use Drives Resistance

Steps:

• Identify common factors: Overprescription (1), agricultural use (2), and incomplete treatment (3) are typical contributors.
• Evaluate each: Overprescription alone doesn't directly cause resistance without exposure; agricultural and incomplete use select for resistant strains.
• Eliminate incorrect combos: Options including 1 overstate its role without context.
• Confirm D: Matches factors 2 and 3 as primary human-driven increases.

Why D is correct:

• Agricultural overuse (2) and incomplete courses (3) create strong selective pressure, per Darwinian evolution, favoring resistant bacteria survival.

Why the others are wrong:

• A includes 1, but overprescription is secondary without direct selection.
• B omits 3, ignoring how unfinished treatments allow resistant mutants to persist.
• C omits 2, downplaying livestock antibiotics' role in 70% of U.S. usage.

Final answer: D