Consider the integrity constraints mentioned under Column 1 and their usage under Column 2. Choose the best matching between Column 1 and Column 2.
| Column 1: | Column 2: |
| P. Not null constraint | 1. No two tuples in the relation can be equal on all the listed attributes |
| Q. Unique constraint | 2. Any foreign key field must agree with the primary key that is referenced by the foreign key |
| R. Check clause | 3. Prohibits the insertion of a null value for the attribute |
| S. Referential integrity | 4. Specifies a predicate P that must be satisfied by every tuple in a relation |
1
P-3, Q-1, R-2, S-4
2
P-3, Q-2, R-4, S-1
3
P-3, Q-1, R-4, S-2
4
P-1, Q-2, R-3, S-4