Choose the alternative which can replace the bold word

Solution

The word "eccentric" means strange or unconventional in behavior. We need a synonym that closely matches this meaning.

Conventional means typical or ordinary, which is the opposite of eccentric.

Mysterious implies something difficult to understand, but not necessarily unconventional.
Unusual correctly matches the meaning of "eccentric", indicating something out of the ordinary.
Ordinary is opposite of eccentric; implies something normal or usual.