Studies of rats deprived of maternal contact showed that the rats developed permanent deficits in the hippocampus. such deficits (in rats or humans) could make them more vulnerable to:

a. aggression

b. depression

c. introversion

d. sexual promiscuity

The answer will be letter b, depression. It is because of maternal contact it makes rats have permanent deficit in the hippocampus, where in the hippocampus is found in the brain that controls emotion or memory and when having a deficit, it shows that they will likely have low or poor emotions which would describe that they are vulnerable to depression.