প্রশ্ন ও সমাধান

Exactly six RAB officers - S, T, U, X, Y, and Z- take turns watching a suspect. To minimize the chance that the suspect will observe them or will escape their surveillance, the officers will operate according to the following conditions:There must be exactly two officers watching the suspect at all times. Whenever the suspect travels by car, either U or X must be one of the two officers watching, but U and X cannot take a turn together.Whenever the suspect travels by train, either Tor Z must be one of the two officers watching, but T and Z cannot take a turn together. If Z is one of the officers watching the suspect, S must be the other officer watching the suspect. S and X cannot take a turn together watching the suspect.If Y is one of the officers watching the suspect, which of the following cannot be the other officer watching the suspect?