Explanation:

- The idiom "Man of letters" refers to a person who is proficient in literature or scholarly pursuits.

- Option 1: Dancer - This is unrelated as it refers to someone skilled in dancing, not literature.

- Option 2: Scholar - A scholar is someone who studies and has extensive knowledge, especially in literature and related fields.

- Option 3: Singer - Similar to dancer, this is unrelated to literature or scholarly endeavors.

- Option 4: Actor - This is someone skilled in acting and performing, not related to literary scholarship.