Referential integrity means

A. 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

B. Do not 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

C. 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

D. All of above

Answer: Option A