In the Northern Hemisphere, the magnetic compass will normally indicate a turn toward the south when

Explanation

On east or west headings in the Northern Hemisphere, acceleration makes the compass indicate a turn toward the north and deceleration a turn toward the south (remembered as ANDS). Decelerating on a west heading therefore shows a turn toward the south. Turns from east or west headings produce little turning error, so the compass shows the actual turn toward the north in the other options.