The correct answer is: Expert.
An expert is a person who has a comprehensive and authoritative knowledge of or skill in a particular area. They are typically highly trained and experienced in their field, and their knowledge and skills are often sought after by others.
A snob is a person who looks down on others because they think they are better than them. They are often arrogant and condescending, and they may put others down in order to make themselves feel superior.
A literate person is someone who can read and write. They have the ability to understand and use written language, and they are often well-educated.
An intellectual is a person who is concerned with ideas and theories. They are often highly educated and have a deep understanding of complex issues.
In this case, the correct answer is expert because it is the only option that describes a person who has a comprehensive and authoritative knowledge of or skill in a particular area. The other options do not accurately describe the person in the question.