How does the motive political encourage imperialism?

Patriotism and growing imperial power spurred countries to compete with others for supremacy. It's a matter of national pride, prestige and security. Empires sought strategic territory to ensure access for their navies and armies around the world. The empire must be defended and, better yet, expanded.

(b) britain had a much larger navy than the u.s.

(d) the u.s. had a small army compared to britain.