Answer: E. all of the above.
Explanation: for human infants to grow and develop normally, the need for them to interact with people (family, friends and the public) cannot be over emphasized. Interaction with people goes a long way in the brain, physical and social development of infants.
Frequent interaction with people helps infants in their communication skills.
Respiratory system and Circulatory system :P
The correct answer is the circulatory system. Hope that helps :)
