Refer to figures.
The feedback for this question was weak and there is another recently added question which asks a similar question in the opposite manner (Q814718 - originally seen in Austro Control), so any feedback you have about either of these questions from the real exam would be very useful to make sure this question is representative of the real exam, thank you very much.

This is quite a tricky question as the examiner is almost trying to get you confused about which stability they are discussing. The spiral dive occurs as a link between strong directional (yaw) stability but weak lateral (roll) stability. Imagine an aircraft is disturbed to roll slightly right, and therefore takes up a slight right sideslip. The large fin yaws into the turn before the aircraft can roll out of it, and this yaw causes a further bank, which again causes more yaw before the aircraft can roll out of it. During this process, the nose keeps dropping to increase airspeed to maintain lift in the turn without any increase in angle of attack.

In IMC without good use of instruments, this feels like straight and level flight until the G forces start to increase noticeably, at which point the pilot would finally notice that something was wrong, as they are in a high speed spiral dive.

But now back to the theory. Many aircraft have a slight spiral instability, which, even though the aircraft might be statically stable in all axes, means that a small departure from straight and level will gradually become a spiral dive if no pilot inputs are made. As this is a gradual process, it is acceptable up to a certain rate of instability as the pilot can easily override it. Being stable in the spiral mode means that the aircraft naturally tends to reduce any spiral dives to zero. If an aircraft is stable in the spiral mode, then it is likely to have a strong tendency for dutch roll.

For this question, then, if the aircraft's rate of turn, rate of descent and speed are all decreasing, then it is naturally rolling out of the turn, and is therefore stable in the spiral (dive) mode.