The speech he made on the occasion was quite exhilarating.

Answer: Option C

Irrelevant : not connected with or relevant to something.
Boring : not interesting; tedious.
Lively : full of life and energy; active and outgoing.
Learned : (of a person) having acquired much knowledge through study.
Exhilarating : making one feel very happy, animated, or elated; thrilling.

Synonym of Exhilarating is Lively