The answer would be : <span>lithium.
Hope this helps !
Photon</span>
A will be the answer because usually marking your exercise days will become a habit because lets say you would do a running exercise but you want to do it in a certain day well if you mark it on the calendar, it'll become a habit.
Answer: This is it Katherine will be promised a reward if she initiates contact with another person.
Explanation: FACTS
