Orographic precipitation occurs due to the presence of mountain barriers. When air masses encounter a mountain range, they are forced to rise to higher altitudes, which leads to the formation of clouds and precipitation. This process is also known as orographic lifting.

Here is a detailed explanation of why the correct answer is option 'C':

1. Orographic Lifting:
When air masses approach a mountain range, they are forced to rise because of the physical barrier created by the mountains. As the air is lifted, it cools adiabatically (due to expansion), and the water vapor it contains condenses to form clouds. The lifting of air over the mountains is called orographic lifting.

2. Condensation and Precipitation:
As the air continues to rise, it cools further, and the moisture in the air condenses into water droplets or ice crystals, forming clouds. These clouds can then produce precipitation, such as rain, snow, or hail, depending on the temperature at different altitudes. The amount of precipitation depends on the moisture content of the air and the duration of the lifting process.

3. Rain Shadow Effect:
Once the air mass reaches the top of the mountain range, it begins to descend on the leeward side of the mountains. As the air descends, it warms adiabatically (due to compression), causing any remaining moisture to evaporate. This results in a dry region on the leeward side, known as the rain shadow, where little or no precipitation occurs.

4. Enhanced Precipitation on Windward Side:
On the windward side of the mountains (the side facing the prevailing winds), orographic lifting enhances precipitation. The moist air is forced to rise, leading to the formation of clouds and precipitation. This side of the mountains typically receives more rainfall than the surrounding areas.

5. Examples of Orographic Precipitation:
Orographic precipitation is commonly observed in mountainous regions around the world. For example, the Pacific Northwest in North America experiences heavy rainfall due to orographic lifting caused by the coastal mountain ranges. Similarly, the Western Ghats in India and the Andes Mountains in South America are known for their significant orographic precipitation.

In conclusion, orographic precipitation occurs when air masses encounter mountain barriers and are forced to rise, leading to the formation of clouds and precipitation. The presence of mountain ranges creates a physical barrier that causes the air to lift and cool, resulting in condensation and precipitation. This process plays a crucial role in determining the distribution of rainfall in mountainous regions.