What point is Roosevelt trying to make in this
speech?

This is part of a radio speech delivered by President Roosevelt in December 1940 (this was the second year in WWII, and the US was still neutral in the conflict).

He aimed to convince the audience about the necessity of ensuring a safe defense strategy for Great Britain, so that they were able to avoid the German invasion and resist the many attacks they were suffering.

Apart from the ideological fight against nazism, Roosevelt highlighted how if GB fell, the last territory in the Atlantic, before reaching the US, would have been conquered. That would pose a direct threat on the US. Therefore, he supported the idea that GB should remain free at any cost.

Explanation:

answer: (fluidity)is the correct answer.

explanation: because of this characteristic, success on the battlefield depends in large part on the ability to adapt to proactively change events to our advantage as well as to react quickly to constantly changing conditions