Irrelevant—this doesn’t rule out any alternative explanations for the spiders’ behavior. It makes sense that plants are more productive when protected from leaf-eating insects, but (A) doesn’t address whether the spiders themselves are actually protecting the plants.

This strengthens the author’s hypothesis by validating a prediction that would follow from it. If his hypothesis were true, we’d expect to see the plants thriving and reproducing when the spiders are introduced, since the spiders protect them from leaf-eating insects.

Irrelevant— this fails to address whether jumping spiders are protecting the plants from leaf-eating insects and thus fails to strengthen the argument.

Irrelevant— the argument is only concerned with whether or not the jumping spiders defend EFN-producing plants. The effect of other types of spiders on EFN-producing plants doesn’t matter.

Irrelevant— we already know that certain ants protect EFN-producing plants from leaf-eating insects, so it makes sense that areas with lots of ants also have lots of EFN-producing plants. But (E) fails to address whether jumping spiders also protect these plants.