We can find the orthogonal vector when we use the dot product.
Then, the result must be equal to zero.
The vector u is given by coordinates <-7,-4>
Then, we need to find a vector in which their dor product will be equal to zero:
<-7,-4>*<1/7,-1/4> =-7*1/7 +(-4)*-1/4 = -1+1 =0
Therefore, the orthogonal vector is <1/7,-1/4>
The correct answer is option B