Use the Following Information and Figure to Answer the Question

Use the following information and figure to answer the question.
Aphids are Hemiptera that suck phloem liquid from plants. Ants are often seen tapping the posterior end of the aphid and collecting the liquid that is released from the aphid's digestive system. In an effort to understand this interaction, several researchers measure the survival rates of aphid populations when ants were present and when they were excluded. Their results are shown.

Imagine that you wished to discover if the ants protect the aphids from flying predators. You would exclude ants from the plants and count aphid population size under two conditions. Which of the following experiments would best help answer this question?

A) plants covered by netting versus not covered by netting
B) plants with stems coated at the base with a sticky substance versus not coated with a sticky substance
C) plants with extra fertilizer and water versus no extra fertilizer and water
D) plants sprayed with insecticide versus not sprayed with insecticide