Describe the motion of a cold air mass and a warm air mass and the weather you would expect at a warm front and an occluded front

It would cause Rain. But a cold front. Fronts are always in relation to moving cold air A cold front is the advancing edge of a cold air mass and a warm front is the retreating edge of a cold mass. If the cold air mass is displacing the warm air front then the cold air is advancing. 

The answer is option a.