Look at this system of equations.
-3x+3y=12
y=x+4
The solution set of this system is best explained by which of these statements?

A
The graphs of the equations are parallel lines because they have the same slope but different y-intercepts. The system has no solution.

B
The graphs of the equations are the same line because the equations have the same slope and the same y-intercept. The system has infinitely many solutions.

C
The graphs of the equations are lines that intersect at one point because the equations have the same slope but different y-intercepts. The system has exactly one solution.
D
The graphs of the equations are lines that intersect at one point because the equations have the same slope and the same y-intercept. The system has exactly one solution.