The effect __ the drug isnt as great as the advertisement says.A.of B.on 该选哪个呢?

题目

The effect __ the drug isnt as great as the advertisement says.A.of B.on 该选哪个呢?

答案

答案：A.
翻译：这个药的功效并不如广告上所说的那样好.
根据句意,明显为名词所有格形式.
the effect of the drug = the drug's effect 这个药的功效
如果用on,则句意为“某物对这个药物的功效”,句意不通.