Choose the word that can substitute the given group of words.

One who does not express oneself freely

Introvert

The word that can substitute the given group of words is introvert. It means "a person who is shy or inward-looking and does not enjoy social interaction." The other options are incorrect.

• Skeptic means "a person who doubts the truth of something."
• Erudite means "having or showing great knowledge or learning."
• Pessimist means "a person who tends to see the worst side of things or believe that things will go wrong."