Assertion. The GROUP BY clause yields summary results using group functions.

Reason. The GROUP BY clause combines a number of rows in a group and applies functions on it.

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
The GROUP BY clause yields summary results using group functions because it combines all records that have identical values in a particular field or a group of fields. This grouping results in one summary record per group if group functions are used with it.