conducted ingenious research which demonstrated that infant monkeys become attached to a terrycloth-covered "mother" and would cling to it rather than a wire mother that provided them with food.

The correct answer is Harlow.

Attachment theory focuses on the psychological phenomena that happen when we establish affective bonds with other people. The way we do this will be conditioned on how our parents related to us during childhood. Therefore, many times, if the relationship was not positive, some types of toxic relationships may end up or that end in emotional dependence.