The resultant of ` vec(a)` and ` vec(b)` makes `alpha` with `vec(a)` and `beta` with `vec(b)`, then (a,b represent magnitudes of respective vectors) :
A. `apha lt beta`
B. `alphagt beta "if" Alt B`
C. `alpha lt beta "if" A=B`
D. `alpha lt beta "if" Alt B`