Question

An author is most likely to create and increase tension in which part of a narrative or story? Exposition Falling action Resolution

Answer 1

the climax... the main part where the problem is

Answer 2

Action

Exposition is just explaining stuff or describing stuff.
Falling is the release of the action after the climax
Resolution is tying up all the loose ends

You create tension during the action until you build into the climax.

Hope that helps.