The right option is; B. cold
A cold front is a type of collision in which cold, dense air displaces warm air, and forces the warm air up along a steep slope.
Cold front is the boundary of a cooler mass of air that replaces a warmer mass of air at ground level which is positioned within a fairly sharp surface of a low pressure system. Cold fronts normally move from northwest to southeast and they are usually weak in the summer and strong in the spring and fall. Cold front causes thunderstorms, rain and strong shifting winds.
