When looking at a relationship between two tables on an erd, the table can be identified by the presence of a foreign key constraint.
a) parent
b) child
c) lookup
d) value

A

Explanation:

ERD diagram is a diagram which can illustrate the relation ships between different entities in a database. When we are referring the values of parent table in child table ,then a foreign key constraint will exist on child table to the parent table.so by looking at that foreign key constraint on child table we can identify the parent table. If we try to insert some value in child table which doesn't exist in parent table it will throw the foreign key violation error .

The Answer is A