In one study, rats licked frequently during infancy by their mothers were calmer than rats licked
infrequently when faced mm stress later in life. What is the most likely explanation for this?

a The rat pups that were frequently licked learned to engage in the licking behavior as a

. coping strategy during times of stress.

b Because mothers M10 chose to lick their pups had a calmer demeanor, their pups were

. raised in less stressful environments.
c By licking their pups, these mothers had influenced the expression of genes that

. influenced responses to a stress hormone.

d The "licking" prone mothers only cared for the calmest pups of the litter, causing the
. more aggressive pups to die prematurely.