Answer & Explanation
B) Tailor and cook
Clealry, C and D sit opposite to each other. So, if A sits opposite to cook, B shall be the cook.
Now, B is to the right of barber. So, one of the rest, say C will be barber.
Clealry, then D on the opposite side shall be washerman or tailor. But, washerman is left of tailor and D on the left of A.
So, D is washerman and A is tailor.
Thus, A and B are Tailor and Cook.