What is Cope's Rule, and what is a potentially valid explanation for Cope's Rule as an driven evolutionary trend, at least for any animal species that swims, crawls, or walks? Why should this explanation not apply in the case of foraminifera?

Answer and Explanation:

Copes rule says that there is a tendency for the lineages if organisms to increase in body size as time goes by. A bigger size would make it more possible for animal species that walk crawl or swim to catch preys, get food, and also fight other animals that prey on them.

This is not applicable to animals that fly. The reason is that such animals ought to have lightweight for flight. A bigger size would hinder this. Formainfera are small and they have just a single cell. If they were larger then more cells would be needed and then they would cease being formainfera.