Final answer:
Fronts slope back from the Earth's surface and over cooler dense air, as the cool air is denser and forces warmer air to rise, leading to cloud formation and precipitation. The correct answer is option: b) Cooler.
Step-by-step explanation:
Fronts slope back from the Earth's surface and over cooler dense air. When a front, which is the boundary separating two masses of air of different densities, moves into an area, the less dense warmer air is forced to rise over the more dense cooler air. This is because cooler air is denser than warmer air.
As the warm air rises, it cools down, and its capacity to hold moisture lessens, frequently leading to the formation of clouds and precipitation. This concept is important in understanding weather patterns and the formation of various types of fronts, such as cold fronts and warm fronts.