Which conditions are necessary for the formation of thunderstorms?

The formation of thunderstorms is primarily dependent on three key conditions: high humidity, unstable air, and a lifting force.

High humidity provides the necessary moisture in the atmosphere, which is essential for the development of clouds and precipitation. As the air rises and cools, this moisture can condense, forming water droplets and clouds.

Unstable air refers to air that is warmer at lower altitudes and cooler at higher altitudes, promoting vertical development. In an unstable atmosphere, when the air at the surface is heated, it tends to rise rapidly, facilitating the formation of thunderstorm clouds.

A lifting force, such as a front, mountain range, or thermal updraft, is crucial in initiating the upward movement of air. Without this lifting mechanism, air tends to remain at lower altitudes, hence hindering the development of the necessary cloud structures that lead to thunderstorms.

Therefore, the combination of high humidity, unstable air, and a lifting force creates the ideal conditions for thunderstorms to form, making this the correct choice.