What is it called when a moving warm air mass moves into a stationary cold air mass?

When one of the air masses moves into the other air mass, the stationary front will begin to move. When this transition occurs, the front will then either be classified as a warm front or a cold front, depending on which air mass is pushing ahead. Along some stationary fronts

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The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.