Which word refers to 'a person who has a great deal of knowledge about or skill in a specific subject'?

• A. Specialist
• B. Expert
• C. Authority
• D. Guru

Answer: (B)

The main idea here is finding a word that names someone with extensive knowledge or skill in a subject. An expert is someone who has reached a high level of knowledge or mastery in a specific field through study and practice, which is the standard, formal way to express strong competence. A specialist, while knowledgeable, tends to imply a narrower focus within a field rather than broad mastery. A guru keeps a more informal or cultural tone, suggesting a trusted guide or teacher. An authority refers to someone whose opinions are widely respected or officially recognized, but it doesn’t by itself state the person’s overall level of expertise. Because the prompt emphasizes a great deal of knowledge or skill in a specific subject, expert fits best.