_____  group individuals are called ‘universal donors’.

Persons with ‘O-’ group can give blood to any people as they do not have any antigens on the RBCs. Therefore, such persons are called ‘universal recipients’. Their plasma contains anti-A and anti-B antibodies. 

Persons with ‘AB⁺’ group can accept blood from persons with AB as well as the other groups of blood. Therefore, such persons are called ‘universal recipients’. Their blood plasma lacks anti-A, anti-B and anti-Rh antibodies.