How many people were in each group

A．Most of us don't get enough exercise.
B．We should exercise 15 minutes per day.
C．A high pulse rate is more healthy.
D．Regular exercise can strengthen our heart.

A．They stepped up and down on a bench every day.
B．The didn't do any exercise.
C．They rode on an exercycle every day.
D．They pushed handle bars every day.