Which visual cues indicate that an aircraft is in a spin?

In the scenario of a spin, the key visual cues that indicate this condition include a noticeable rotation around the vertical axis, a nose-down attitude, and a loss of altitude. During a spin, the aircraft experiences a rapidly rotating motion, which is characterized by the nose pointing downward and a significant decrease in altitude due to the stall and subsequent spin dynamics. This combination of factors—specifically the nose-down position and the rotation—clearly distinguishes a spin from other flight conditions.

The other answer choices do not align with the characteristics of a spin; they describe either a stable flight attitude or climbing conditions, neither of which would occur during a spin. Therefore, recognizing the specific cues of a nose-down orientation, rotation, and altitude loss is crucial for identifying an aircraft in a spin.