Larger inhibition zones mean greater antibiotic effectiveness

Steps:

• Identify zone sizes for each antibiotic from the chart.
• Compare sizes: largest zone indicates most effective antibiotic; smallest indicates least effective.
• Match largest to most effective and smallest to least effective.
• Select option pairing these correctly.

Why A is correct:

• Option A pairs the antibiotic with the largest inhibition zone (most effective) and the one with the smallest (least effective), per the disk diffusion method where zone diameter measures susceptibility.

Why the others are wrong:

• B pairs a medium zone as most effective and another medium as least, ignoring actual size extremes.
• C incorrectly assigns a large zone as least effective, reversing the size-effectiveness relationship.
• D swaps two medium zones, failing to identify true maximum and minimum sizes.

Final answer: A