Referential integrity means

1. Do not enter a value in the foreign key field of a child table if that value does not exist in the primary key of the parent table
2. Enter a value in the primary key field of child table if that value does not exist in the primary key of the parent table
3. Do not enter a value in the foreign key field of a parent table if that value does not exist in the primary key of the child table
4. All of above

The Right Answer is : Option A

Explanation