If You Study 3 Hours for an Exam, You Can

If you study 3 hours for an exam, you can raise your score by 30 points. If you study for another 3 hours your score increases by 10 points. And if you study for another 3 hours, your score will increase by 5 more points. A graph displaying this relationship between the number of hours studied and your total exam score would show

A) a positive linear relationship.
B) an upward-sloping curve that becomes less steep.
C) a negative linear relationship.
D) an upward-sloping curve that becomes more steep.