Answer:
C. An activity tracking tool that you wear on your wrist.
Explanation:
A is only for diet not excercise and probably wouldn't be too entertaining.
B is only for blood pressure and glucose and would not be very entertaining or engaging.
C could be entertaining and engaging because usually things like these have little mile markers and badges if you complete certain excercises.
D could also possibly be entertaining and engaging since apps like that are similar to C but it is only for high intensity workouts.
Therefore C is probably the best answer.
