Let Y=-9 X+221 Represent the Number of Students

Multiple Choice

Let y=-9 x+221 represent the number of students present in a large class, where x represents the number of hours of study required weekly. What is the rate of change of the number of students in the class with respect to the number of hours of study?

A) 9 students per hour of study time
B) -221 students per hour of study time
C) 221 students per hour of study time
D) -9 students per hour of study time