Vector v has its initial point at (7, -9) and its terminal point at (-17, 4). Which unit vector is in the same direction as v?

The answer is the option C 
Find unit vector.Definition of unit vector :u is a unit vector, it has the same direction as v then v--------------(7,-9)         (-17,4)v=(-24,13)u is a unit vector, it has the same direction as v
magnitude of v---------(-24^2+13^2)^0.5=725^0.5 u=(-24/(725)^.5),(13/(725)^.5)