Pls help stuck on this

Which of the following requires the action of a first class lever in the body

Which of the following is an important function of child-directed speech? (a) it captures the infant’s attention and maintains communication. (b) it reduces the occurrence of infantile amnesia for the earliest memories of infancy. (c) it reduces the need for reciprocal interaction between caregivers and children. (d) it assists in prolonging rem sleep in infants.

What is the hormone in your brain that makes you feel happy?