Refer to figure.
Cold Front thunderstorm is often violent and likely to cause the formation of Tornadoes. It is formed when a mass of cold air faster than the warm front passes under it. So warm, moist air lighter than cold air, rises creating updrafts and, therefore, a Cumulonimbus.

When a cold front approaches a mountain range, much of the cold air will initially be held back by the range. When this unstable air finally breaks over the mountains, lifting will occur with the additional orographic lifting - which often results in increased thunderstorm intensity

• The result can be heavy banks of Cumulonimbus clouds, with squal lines, very heavy showers, thunderstorms, hail and poor visibility.

“The passage of a warm front in the morning.”→ INCORRECT. Although warm fronts can trigger thunderstorms, they are more likely to be associated with large regions of gentle ascent (stratiform clouds and light to moderate continuous rain).
"A cold front on the leeward side of a mountain range." → INCORRECT. Intense Thunderstorms are normally developed on the upwind side of the mountains.