Concept:The correct word must express the idea of two legislative chambers assembling together for a formal session.
Explanation:The sentence describes the House and the Senate gathering at a specific time to listen to the President.
Such official meetings require a word that means "to assemble" or "to come together."
"Convene" fits this meaning exactly.
It is used for formal gatherings of committees, parliaments, or similar bodies.
"Collude" means to plot or conspire secretly, which has a negative meaning and does not fit the formal context.
"Adjourn" means to end or postpone a meeting, which is the opposite of what the sentence requires.
"Rise" refers to ending a session, not beginning one.
Therefore, only "Convene" correctly completes the gap in meaning and grammar.
Answer:B. Convene.