Using Triggers

You want to use both triggers and integrity constraints to define and enforce any type of integrity rule. In which of the below given scenarios can you use triggers to constrain data input when working with a Oracle database?

1. To enforce complex business rules not definable using integrity constraints.

2. When a required referential integrity rule cannot be enforced using PRIMARY KEY.

3. When a required referential integrity rule cannot be enforced using DELETE SET NULL.

Options

1. Only 1 and 2
2. Only 2 and 3
3. Only 1 and 3
4. All 1, 2 and 3