The conclusion of the argument is: Being near woodlands, the natural habitat of bees, promotes the health of crops that depend on pollination.
Why? Bees visit flowers that are far from woodlands less often than they visit flowers close to woodlands.
The gap in the argument is that we don't necessarily know what happens when a bee visits a flower. The reason the argument gives to prove that being near the natural habitat of bees promotes the health of crops that depend on pollination is that bees visit flowers far from woodlands less often than they visit flowers close to woodlands. But, have we been told that bees visiting flowers means they are going to get pollinated? What if a bee visiting a flower does not help a flower get pollinated? Then the argument's premise does nothing to help us reach our conclusion.
Answer choice (A) bridges the gap in the argument: "The likelihood that a plant is pollinated increases as the number of visits from pollinators increases."
Thus, answer choice (A) strengthens the argument because it explains why the fact that bees visit flowers far from woodlands less often than they visit flowers close to woodlands helps us infer that being near woodlands--the natural habitat of bees--promotes the health of crops that depend on pollination.
Hope that clears things up! Please let us know if you have any other questions.
