A frame of reference `F_(2)` moves with velocity `vecv` with respect to another frame `F_(1)`. When an object is observed from both frames, its velocity is found to be `vec(v_(1))` in `F_(1)` and `vec(v_(2))` is equal to
A. `vec(v_(1))+vecv`
B. `vec(v_(1))-vecv`
C. `vecv-vec(v_(1))`
D. `|vec(v_(1))-vecv|(vec(v_(1)))/(|vec(v_(1))|)`
