Answer:
The correct answer is option b. cold front.
Explanation:
A front is the line of union between two air masses with different temperature, humidity, atmospheric pressure, wind speed and direction.
A cold front is the line that divides a mass of cold air that moves and collides with a mass of hot air that displaces it.
The air masses do not mix, but they push each other. If a mass of cold air pushes the mass of hot air and as the cold air is denser, it moves quickly stuck to the surface forcing the hot air to rise, since it is lighter.
When the hot air is humid and unstable, colliding with a cold front cools and condenses, it causes heavy rains, hail, high winds and thunderstorms.
If the hot air is humid but stable, it will only cause a light rain, but it can bring strong winds.
