According to the author of passage 1, one of the reasons why dodo birds were so large is that they choose 1 answer: (choice

a. a competed with larger birds, such as the haastâs eagle. (choice

b. b had food sources that included large, terrestrial animals. (choice

c. c interbred with the larger, flightless moa. (choice

d. d had no natural predators on the island of mauritius.

The answer to this question would be: d had no natural predators on the island of Mauritius.

To answer the question, you just need to read the article in passage 1. This was written there:

When the dodo's ancestor (thought to be a migratory pigeon) settled on this island with abundant food, no competition from terrestrial mammals, and no predators, it could survive without flying, and thus was freed from the energetic and size constraints of flight.

The reason should be because there is no predator there so dodo doesn't need to fly.