Answer
c)
Work Step by Step
It is equal to the box's weight. After all, it is at a 45 degree angle to the slope, and gravity is 45 degrees to the slope. As a result, the components of each force are equal, making the overall forces equal as well. However, it is important to note that if the slope is not 45 degrees, these components would no longer be at the same angle, so they would no longer be equal.