Harlow Raised Infant Monkeys in Cages with Either a Cloth

Harlow raised infant monkeys in cages with either a cloth or wire "mother". Which of the following was one of Harlow's discoveries that led him to be called "the most influential comparative psychologist of the second half of the 20th century"?

A) infant monkeys deprived of their mother's love would not survive
B) monkeys typically cling to themselves, cry, and rock back and forth in response to stressful situations
C) monkeys derived comfort from feeding and would overeat in response to stressful stimuli
D) perceived security from a cloth surrogate was essential for infants to soothe themselves in response to stress