Which is the purpose of the following short sentence in President Kennedy’s speech?

This much we pledge—and more.
It acts as a transition to the part of his speech in which he addresses his promises to the country and world.
It acts as a reflection of the major points he has made regarding America’s promises.
It acts as a brief summary of the main focus of his speech.

Question

Which is the purpose of the following short sentence in President Kennedy’s speech?

This much we pledge—and more.
It acts as a transition to the part of his speech in which he addresses his promises to the country and world.
It acts as a reflection of the major points he has made regarding America’s promises.
It acts as a brief summary of the main focus of his speech.