Assertion (A): Aggregate functions in SQL operate on multiple set of values and return a single value as the output.

Reasoning (R): The aggregate functions are used to perform some fundamental arithmetic operations such as MAX(), MIN(), SUM() etc.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Explanation
Aggregate functions (multiple-row functions) in SQL operate on multiple sets of values and return a single value as the output. Some common aggregate functions are SUM(), MAX(), MIN(), etc., which are used to perform fundamental arithmetic operations on groups of values.