Question

monarch butterflies in mexico fly to the southern united states in the spring to breed. what are the butterflies doing? immigrating to the united states remaining in the united states hibernating in the united states emigrating from the united states

Explanation:

The text states monarch butterflies in Mexico fly to the southern United States to breed. Immigration is the act of coming into a country from another. Since they are coming into the US, they are immigrating.

Answer:

immigrating to the United States