Which of the following is the psychological perception of sound amplitude?

Which of the following is true of exercise

a. virtually no benefits are obtained unless one gets aerobic exercise, for at least 20 minutes, three times per week b. virtually no benefits are obtained unless one gets aerobic exercise, for at least 30 minutes, three times per week c. moderate, minimally-structured physical activity is nearly as effective in promoting health as other, more regimented programs d. following an exercise program of some sort is necessary for mental, but not physical, health e. following an exercise program contributes to physical health but has no impact on mental or emotional status

In simple language, Freud's concept of __________ involves "letting off steam" or "getting it out of your system."

FIll in the blank with correct word.