What is the effect on groundspeed when an airplane turns from a headwind to a tailwind?

When an airplane turns from a headwind to a tailwind, the groundspeed will increase due to the change in wind direction and speed affecting the aircraft's relative motion across the ground. A headwind works against the aircraft's forward speed, reducing the groundspeed. Conversely, when the aircraft turns and faces a tailwind, the wind now contributes additional speed to the aircraft's forward motion.

For instance, if an aircraft is flying at 200 knots in still air and encounters a headwind of 25 knots, its groundspeed would be 175 knots (200 knots - 25 knots). However, if the aircraft then turns and encounters a tailwind of 25 knots, its groundspeed would increase to 225 knots (200 knots + 25 knots). This capability of the wind to either hinder or aid the aircraft's speed is why the change from headwind to tailwind results in an increase in groundspeed, confirming the correct choice.