Freya is training for a track race. She starts by sprinting 200 yards. She
gradually increases her distance, adding 5 yards a day for 21 days.
Which explicit formula models this situation?

A. a n = 200+ (n - 1)5
B. a n = 5+(n-1)200
C. a n = 200+ (n - 1)21
D. a n= 21 + (n - 115