What Did Psychologists Harry Harlow and Margaret Harlow Do in a Series

What did psychologists Harry Harlow and Margaret Harlow do in a series of laboratory experiments?

A) They isolated human infants and studied them in separate environments.
B) They took infant rhesus monkeys from their mothers and isolated them in separate cages.
C) They determined that,unlike human beings,lower primates do not suffer ill effects from social isolation.
D) They showed that social isolation has many positive effects on behaviour.