Answer:
As the gradient gets more steep, the erosion will increase due to the increased velocity of the stream, hence making it easier to carry loads and erode the surface.
As the load of the stream increases, it will bring more debris and load with it, snowballing the amount of load/debris that the stream carries.
And finally, as the discharge of the stream increases, there is more stream to pick up loads, and erosion will increase.
TL;DR all three will increase erosion.
Explanation:
Hope this helped!