In the event of a bomb threat received via service phone, what are your initial questions?

The correct answer focuses on gathering essential information that is critical for assessing the immediate safety risk posed by the bomb threat. By asking, "Where is the bomb?" and "When is it going off?", the Officer of the Deck (OOD) can obtain crucial details that inform the subsequent actions taken to ensure the safety of personnel and the vessel. Knowing the location of the bomb is paramount in determining which areas need to be evacuated or secured, while understanding the timing helps in coordinating a response and preparation for any potential detonation.

The other options, while they might yield useful information in different contexts, do not address the immediate threat as directly as option A does. Questions about the identity of the caller or who placed the bomb are important for later investigation but do not provide immediate tactical information for managing the threat. Similarly, inquiries regarding the size of the bomb or the whereabouts of crew members, while relevant in a broader safety context, do not prioritize obtaining the most urgent and actionable information regarding the bomb itself.