What type of Agave is this or what conditions cause it to grow this tall central trunk?

I can't really say which agave that is.

All agaves form those inflorescences at the very end of their life. The stalk comes up all in one season, blooms, and then the entire plant dies. Usually little baby agaves have already formed around the plant, thus continuing its life.

Possibly Agave chrysantha
This agave is found in Arizona

Welcome to ATP!

Agave also form plantlets on the bloom stalk. I harvested a bunch last week.