Concept:The Factor Theorem states that if x−4 is a factor of f(x), then f(4)=0.Explanation:Let f(x)=x2−x−k.Since x−4 is a factor, substitute x=4 and set the result equal to zero.f(4)=(4)2−(4)−k=016−4−k=012−k=0Therefore, k=12.Answer:k=12So the correct option is B.