On average, how long does the second stage of the birth process, delivery, last?

The arousal theory of motivation would be most helpful for explaining why:

a. recreational skydivers jump out of airplanes. b. hungry fishermen venture across dangerous ocean waters. c. starving prisoners are preoccupied with thoughts of food. d. sexually active teens learn to practice effective birth control.

_______________ are special molecules in the membrane of a receiving neuron's dendrites with which neurotransmitter molecules bind

a. Synapses b. Glia c. Neuromodulators d. Receptor sites