which correctly explains the number of solutions of the following system of linear equations? -3x + 3y = 12 y = x + 4

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

Please explain how you got the answer because I need to learn it.