Many of his aquaintances avoid him because he is so garrulous.

Answer: Option C

Proud : feeling deep pleasure or satisfaction as a result of one's own achievements, qualities, or possessions or those of someone with whom one is closely associated.
Unreasonable : not guided by or based on good sense.
Talkative : fond of or given to talking.
Quarrelsome : given to or characterized by quarrelling.
Garrulous : excessively talkative, especially on trivial matters.

Synonym of Garrulous is Talkative