Final answer:
The system of equations given are actually the same line and every point on this line is a solution, which means the correct answer is C. Infinite solutions.
Step-by-step explanation:
The system of equations given to solve is:
By adding the two equations, we can eliminate both x and y because they are additive inverses of each other. When we add them, we get:
x - 3y - x + 3y = 9 - 9
Which simplifies to:
0 = 0
This is an identity, meaning that the two equations are actually the same line, and therefore every point on the line is a solution. Thus, the correct answer is C. Infinite solutions.