A. (v1 - v2)/(u1 - u2)
B. (v₂ - v₁)/(u1 - u2)
C. (u1 - u2)/(v1 - v2)
D. (u₂ + u₁)/(v₂ + v₁)
Please do not use chat terms. Example: avoid using "grt" instead of "great".