Which of the following would be a plausible smart goal for a person who is new to exercise?
a. rowing five miles solo in 2 hours by the end of the day
b. running a fifteen-mile course in 45 minutes by the end of the week
c. swimming twenty 50-meter laps in 30 minutes by the end of two week
d. walking one continuous mile in 25 minutes by the end of the month