The author believes （）

A．the difficulties of exercising
B．why exercising is good for your health
C．important information to know about exercising
D．why people have some wrong ideas about exercising

A．telling readers to exercise for five minutes a day
B．pointing out wrong ways in exercising
C．giving examples of beneficial exercise
D．comparing the results of beneficial exercise and too much exercise

A．You use the same amount of energy whether you jog or walk for the same amount of time.
B．You use the same amount of energy whether you jog or walk the same distance..
C．You use more energy if you jog rather than walk the same distance.
D．You use more energy if you walk rather than jog for the same amount of time.