He was the most eccentric and difficult patron.

normal
sober
genial
sociable

The correct answer is A. normal.

An eccentric person is someone who behaves in a way that is unusual or strange. A difficult person is someone who is hard to please or deal with. A normal person is someone who behaves in a way that is typical or usual.

B. sober is not the correct answer because it means not drunk.
C. genial is not the correct answer because it means friendly and pleasant.
D. sociable is not the correct answer because it means friendly and outgoing.