Question

blue whales make loud noises under the water. other whales hear these calls. then, they make loud noises, too. this is how blue whales talk to one another. why do blue whales make loud noises under the water? they are looking for their home. they are talking to other blue whales. they are yelling at sharks.

Explanation:

The text states "This is how blue whales talk to one another." when referring to the loud noises they make. So we can infer the reason from this sentence.

Answer:

They are talking to other blue whales.