The correct frequency of exercise in order for it to be effective is

a. at least twice a day.
b. at least seven times per week.
c. a maximum of eight times per week.
d. a minimum of three to five times per week

For exercise to be efficient, you must engage in a meaningful exercise at least three to five times a week. Exercising too little won't engage your muscles and body like it should. Conversely, too much exercise on your body won't allow it any time to heal itself from strain and exertion.

Imma gonna say go with the very first answer (: