Concept:Factor out the common variable k from the left-hand side, then isolate k.Explanation:Start with the given equation:ky−k=y2Factor k out of both terms on the left:k(y−1)=y2To make k the subject, divide both sides by (y−1):k=y−1y2Thus, k is expressed in terms of y.Answer:k=y−1y2So the correct option is A.