A bus has exactly six stops on its route. The bus first stop one and then at stops two, three, four, five, and six respectively. After the bus leaves stop six, the bus turns and return s to stop one and repeats the cycle. The stops are at six buildings that are, in alphabetical order L,M,N,O,P and Q P is the third stop M is the sixth stop. The stop O is the stop immediately before Q. N is the stop immediately before L. Q: In case L is the second stop, which among the following must be the stop immediately before M?