The first one is C!
I hope the answer helped! please mark brainliest and vote 5 stars! >:)
The net force is 0 N.
To find the total net force, all you need to do is add the forces.
So 100 + -100 = 0
Most of these questions are trick questions, but if you know Newton's laws of forces, then you should know that all forces should cancel out with each other.
Hope this helps!!!
If we're talking about part c then
igneous rock + weathering and erosion = sedimentary rock
sedimentary rock + heat and pressure = metamorphic rock
magma + cooling = igneous rock