Concept:If the solution set contains x=−1 and x=5, then x+1 and x−5 are factors of the quadratic expression.Explanation:Write the equation using these factors: (x+1)(x−5)=0.Expand the product: x2−5x+x−5=x2−4x−5.Compare this with the given equation x2+kx−5=0.The coefficient of x in the expanded form is −4, so k=−4.Answer:k=−4, which is option B.