The error messageYou cannot add or change a record because a related record is required in table 'Countries'.will be generated by attempting which of the following with the Megacities database?a$.$A user tries to enter a record in the table Countries that doesn't contain data in the primary key.b$.$A user tries to add a record to a table that is related to the Countries table, and that record contains a foreign key value that does not correspond to a primary key value in the Countries table.c$.$A user tries to enter a record to the table Countries with the same primary key as another record.d$.$The user tries to request a joined table using LINQ.