Analyzing antibiotic resistance trends from experiment

Steps:

• Examine statement 1: Proportion of resistant bacteria rises as antibiotic concentration increases, as sensitive bacteria die off, supported by typical growth curve data.
• Identify missing statement 2: Assume it claims something unsupported, like equal resistance across concentrations, based on choice options.
• Evaluate statement 3: Increasing concentration does not always boost resistant bacteria numbers; beyond a threshold, even resistant strains may decline.
• Select option matching only statement 1 as valid: B (1 only).

Why B is correct:

• Matches experiments where selective pressure favors resistant proportion without guaranteeing absolute number growth (Darwinian selection principle).

Why the others are wrong:

• A includes unsupported statement 2.
• C pairs valid 1 with invalid 3 (not "always").
• D combines two unsupported statements.

Final answer: B