One reason why kangaroo care works is that it decreases the amount of energy that a preterm infant has to expend, leaving more energy for growth. What mechanism best explains this decreased energy expenditure?
a. The familiar sounds associated with the mother (heartbeat and voice)
b. The calming effect of the mother's familiar odour
c. The mother's assistance in maintaining a constant temperature
d. The release of oxytocin that results from skin-to-skin contact