A car's speed, Y, in miles per hour, after t seconds is given by the function y = S(t).
What is meant by the statement S⁻¹(90) = 15?
a. After 15 seconds, the car has traveled 90 miles.
b. After 90 seconds, the car is at a speed of 15 miles per hour.
c. After 15 seconds, the car is at a speed of 90 miles per hour.
d. After 90 seconds, the car has traveled 15 miles.
e. After 15 seconds, the car has reached cruising speed and will maintain its for another 90 seconds.