A subquery in an SQL SELECT statement is enclosed in:

In SQL, a subquery is enclosed in parentheses, as shown in Option A. Subqueries are used to retrieve data from one table and use that data as a condition for another query. The syntax for subqueries requires using parentheses to enclose the subquery within the main query. Options B, C, and D do not represent the correct way to enclose subqueries in SQL.