Answer:
C. difference of two forces.
Step-by-step explanation:
When forces act in opposite directions, they have opposite signs. For example, if one force is +5 N and the other force is -3 N, the net force would be +5 N - (-3 N), which simplifies to +5 N + 3 N.
This addition of forces with opposite signs is equivalent to subtracting the magnitudes of the forces. In this example, it would be 5 N - 3 N, which equals 2 N.