Based on the graph, which statement is correct about the solution to the system of equations for lines a and b?
a. (4, 2) is the solution to line a but not for line b
b. (4, 2) is the solution to both lines a and b
c. (0, 0) is the solution to both lines a and b
d. (0, 0) is the solution to line a but not for line b