what is a cold front advancing under a warm front called?\na stationary front\na warm front occlusion\na…

Brief Explanations:

An occluded front occurs when a fast-moving cold front overtakes a slower-moving warm front. There are two types of occlusions based on the relative temperatures of the air masses involved. A cold front occlusion occurs when the air behind the advancing cold front is colder than the air ahead of the warm front. In this scenario, the very cold air mass slides under both the warm air mass and the cool air mass associated with the warm front, lifting them both off the ground.

Answer:

a cold front occlusion