Which of the Following Is Not a Forecaster's Rule of Thumb

Which of the following is not a forecaster's rule of thumb?

A) For short time intervals,mid-latitude cyclonic storms and fronts tend to move in the same direction and at approximately the same speed as they did during the previous six hours.
B) Low pressure areas tend to move in a direction that parallels the isobars in the warm air sector.
C) Lows tend to move toward the region of greatest pressure drop.
D) Highs tend to move toward the region of greatest pressure drop.