A mail carrier must deliver mail by making a stop at each of six buildings: k, L, M, O, P, and S. Mail to be delivered are of two types, ordinary mail and priority mail. The delivery of both types of mail is subject to the following conditions: Regardless of the type of mail to be delivered, mail to P and mail to S must be delivered before mail to M is delivered. Regardless of the type of mail to be delivered, mail to L and mail to K must be delivered before mail to S is delivered. Mail to buildings receiving some priority mail must be delivered, as far as the above conditions permit, before mail to buildings receiving only ordinary mail. 17. If K is the only building receiving priority mail, which of the following lists the buildings in an order, from first through sixth, in which they can receive their mail? A: L, K, P, S, O, M B: L, K, S, P, M, O C: K, L, P, M, S, O D : K, P, L, S, O, M E: O, K, L, P, S, M E