In what position should you stand when speaking to an officer?

When speaking to an officer, standing at attention is the appropriate position. This posture conveys respect and acknowledges the officer's rank and authority. Standing at attention involves a straight posture, feet together, arms at the sides, and no movement aside from responding as necessary. This formality signifies discipline and adherence to military protocols.

Positions such as "at ease" or "parade rest" imply a more relaxed stance and are typically reserved for instances when an officer is present but not directly engaging with you in a formal manner. Sitting down would not be suitable in this context as it displays a lack of respect when conversing with someone of higher rank. Therefore, standing at attention is the correct response when interacting with an officer.