The officer of the watch should not hand over the watch to the relieving officer if he has any reason to believe that the latter is apparently under any disability which would preclude him from carrying out his duties effectively. If in doubt, the officer of the watch should inform the master accordingly. The relieving officer should not take over the watch until his vision is fully adjusted to the light conditions and he has personally satisfied himself regarding: (1) standing orders; (2) the position, course, speed and draught of the vessel; (3) prevailing and predicted tides, currents, weather, visibility and the effect of these factors upon course and speed; and (4) the navigational situation. If at the time the officer of the watch is to be relieved a man œuvre or other action to avoid any hazard is taking place, the relief of the officer should be deferred until such action is completed.If the OOW is not sure about the fitness of the relieving officer, he shall firstly _______.A hand over the watchB inform the masterC take over the watchD leave the bridge

我们来逐步分析这道题。

题目内容是关于《国际海上人命安全公约》（SOLAS）和《STCW公约》中规定的值班交接程序，特别是当值班驾驶员（Officer of the Watch, OOW）对 relieving officer（接班驾驶员）是否适合接班有疑虑时应如何处理。

原文关键句是：

> "The officer of the watch should not hand over the watch to the relieving officer if he has any reason to believe that the latter is apparently under any disability which would preclude him from carrying out his duties effectively. If in doubt, the officer of the watch should inform the master accordingly."

翻译为中文：

> 如果值班驾驶员有任何理由相信接班驾驶员显然存在某种障碍，以致无法有效地履行其职责，则不应将值班责任交给他。如有怀疑，值班驾驶员应相应地通知船长。"

题目问的是：

> 如果值班驾驶员（OOW）对接班驾驶员的适任能力有疑问（not sure about the fitness），他应首先做什么？

我们来看选项：

A. hand over the watch —— 交班
B. inform the master —— 通知船长
C. take over the watch —— 接班（这不合逻辑，他本来就在值班）
D. leave the bridge —— 离开驾驶台

根据原文：“If in doubt, the officer of the watch should inform the master accordingly.”
即：如果有怀疑，应通知船长。

所以，当OOW对接班驾驶员的身体或精神状态是否适合接班有疑问时，他不应直接交班，而应首先通知船长，由船长来决定后续处理。

因此，正确答案是：

B. inform the master

解题过程总结：

1. 题干问的是：当OOW对接班驾驶员是否适合接班有疑问时，他应首先做什么？
2. 原文明确指出：如果有任何理由认为接班者无法有效履职，则不应交班。
3. 特别强调：“If in doubt, the officer of the watch should inform the master accordingly.”（如有怀疑，应通知船长）。
4. 因此，第一步不是交班，也不是离开驾驶台，更不是自己去接班（他已经在值班了）。
5. 正确做法是：通知船长，由船长介入处理。

答案：
\boxed{B}