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The following table has two attributes A and C where A is the primary key and C is the foreign key referencing A with on-delete cascade.

A C
2 4
3 4
4 3
5 2
7 2
9 5
6 4

The set of all tuples that must be additionally deleted to preserve referential integrity when the tuple (2,4) is deleted is:

(a) (3,4) and (6,4)                        (b) (5,2) and (7,2)
(c) (5,2), (7,2) and (9,5)               (d) (3,4), (4,3) and (6,4)