A/n front is a type of collision in which cold, dense air displaces warm air, and forces the warm air up along a steep slope.
a. occluded
b. cold
c. stationary
d. warm

The correct answer is B. A cold front is defined as the transition zone where cold air replaces warmer air. It move from northwest to southeast. The opposite of the cold front is the warm front where warmer air replaces a cold air.

It's lithogenous i believe of course i looked it up.