The correct option is C B−C={4,5}
Given three sets: A={1,2,3};B={4,5,6} & C={6,7,8}
Now, B−C={4,5,6}−{6,7,8}={4,5}
Also, A×B={(a,b):∀ a∈A & b∈B}
Similarly, A×C={(a,c):a∈A & c∈C}
And A×(B−C)
={1,2,3}×({4,5,6}−{6,7,8})={1,2,3}×{4,5}={(1,4),(1,5),(2,4),(2,5),(3,4),(3,5)}