If a pair of officers was watching while the suspect traveled by car, and the same pair of officers continued watching after the suspect began to travel by train, one member of that pair of officers must have been

Explanation: এই puzzle টির condition গুলো হল: 1. Exactly 2টি officer কে suspect watch করতে হবে। 2. Car এ travel করলে, U অথবা X কে watch করতে হবে, কিন্তু U এবং X একসাথে watch করতে পারবেনা। 3. Train এ travel করলে, T অথবা Z কে watch করতে হবে, কিন্তু T এবং Z একসাথে watch করতে পারবেনা। 4. Z থাকলে S কেও থাকতে হবে। 5. S এবং X একসাথে watch করতে পারবেনা। Car এবং Train উভয় ভ্রমণের জন্যই একই pair কে watch করতে হবে। Pair = \(\{O_1, O_2\}\). Car এর জন্য: \(O_1\) বা \(O_2\) অবশ্যই U বা X হবে, কিন্তু \(\{U, X\}\) হতে পারবে না। Train এর জন্য: \(O_1\) বা \(O_2\) অবশ্যই T বা Z হবে, কিন্তু \(\{T, Z\}\) হতে পারবে না। If \(Z\) is in the pair, then \(S\) must also be in the pair (Rule 4). \(\therefore\) If \(Z\) is selected, the pair is \(\{Z, S\}\). But the pair \(\{Z, S\}\) cannot watch during car travel because \(S\) and \(X\) cannot take a turn together (Rule 5) and one of them (U or X) must be there (Rule 2), and \(S \neq U\), \(S \neq X\). (Wait, Rule 2 states U or X must be *one* of the two. If the pair is {Z, S}, neither U nor X is present. Hence, {Z, S} cannot watch car travel. The explanation is slightly misleading, S and X cannot be together is Rule 5. The core issue is Rule 2 violation for {Z, S}). Therefore, Z cannot be in the pair. The train pair must contain T. If T is in the pair, the pair could be \(\{T, S\}\), \(\{T, U\}\), \(\{T, X\}\), or \(\{T, Y\}\). Check against all conditions. All listed options are valid except {T, Z} (Rule 3). All valid train pairs must contain T. Thus, T must be a member.