Anorexia nervosa is diagnosed far more frequently in females than in males, equal numbers of males and females are diagnosed with bulimia nervosa

When a stranger began walking behind Timothy on the dark and deserted street, his heart rate increased and the muscles in his legs began moving faster so he could gain some distance from the stranger. These mobilization and motor activities were most directly orchestrated by his ____ nervous system.?

a. ?central b. ?endocrine c. ?peripheral d. ?parasympathetic

Operational definitions:

a. ensure the results of a scientific investigation will be externally valid b. define concepts in terms of how they will be measured c. are only necessary in experimental studies d. define concepts in abstract terms