Answer: A)

B) Slope=200, It means enrollment of 200 students increases each year.
C)

D) 2500 students.
Explanation:
Given: The student enrollment of the high school, P, has increased at a constant rate each year, t, since 2009.
At 2009, t=0 and at 2012, t=3 [Since 2012-2009=3 years]
A) In points , the given enrollment numbers will be written as:-

B) The slope of the line passing through
is given by:-

It means enrollment of 200 students increases each year.
C) The linear equation with slope= 200 and and the initial number of students (900) is given by

D) At 2017, t=8 [Since 2017-2009=8]
Then

The high school's enrollment in 2017 = 2500 students.