Question

would you look down or up to find a city of ants? in the rainforest, look up. an ant city might be in the trees!
weaver ants build nests in trees. a nest can be as big as a soccer ball. an ant city might have 100 nests. a half million tiny weaver ants might live there.
there are two weaver ant nests in this tree.
where do weaver ar build their nests?
in trees
on the ground
in the city

Explanation:

The text clearly states "Weaver ants build nests in trees." This directly answers the question about where weaver ants build their nests.

Answer:

in trees