A patient must give his or her permission before a practicum student participates in patient care

Most cases of depression are believed to be caused by

a. increased activity of norepinephrine neurons. b. genetic factors. c. family or social environment. d. reduced activity of norepinephrine neurons.

Letter D in the figure represents the ________, which forms most of the posterior wall of the larynx.

Fill in the blank(s) with the appropriate word(s).