You have the y-intercept of -4. That means that the line will go through the point (0, -4). Choices B and C do that. Plug in 1 for x and find y.
y = 2x - 4
y = 2 * 1 - 4
y = 2 - 4
y = -2
In graph B, when x = 1, y = -3.5, which is incorrect.
In graph C, when x = 1, y = -2
Graph C is the correct answer.