The correct answer is: A. an ascending gradient meets with another ascending gradient.
A summit curve is a type of curve that is used to connect two different gradients. The deviation angle is the angle between the two gradients. The deviation angle will be maximum when the two gradients are most different. This is when an ascending gradient meets with another ascending gradient.
When an ascending gradient meets with a descending gradient, the deviation angle will be less than when the two gradients are both ascending. This is because the two gradients are not as different.
When a descending gradient meets with another descending gradient, the deviation angle will be the least. This is because the two gradients are the same.
When an ascending gradient meets with a level surface, the deviation angle will be zero. This is because the two gradients are not different at all.