Answer the following question: Fact 1: Earth 's magnetic patterns are used for finding locations by animals that migrate. Fact 2: Bird migration is common. Given the two facts above, earth 's magnetic patterns are used for finding locations by which creatures?

pick from the following.
(I). animals;
(II). Frogs;
(III). bats;
(IV). birds;
(V). dogs;
(VI). humans;
(VII). horses;
(VIII). insects;
Answer:
(IV).