Final answer:
The primary cause of wind is the horizontal pressure difference, as air moves from an area of high pressure to an area of low pressure leading to the creation of wind. This pressure difference is the primary driver of wind strength and direction, although the Coriolis effect and thermal energy also play roles in shaping wind patterns.
Step-by-step explanation:
The primary cause of wind is c) Horizontal pressure difference. Wind occurs when air moves from a region of higher atmospheric pressure to a region of lower pressure. This movement is driven by the goal of equalizing pressure differences across distances, which is why storm reports often emphasize how important pressure is in determining weather patterns. The pressure difference creates wind speed and direction, and when this difference is more pronounced, stronger winds are the result. While the Coriolis effect influences the direction of wind flow due to the earth's rotation, it is not the primary cause of wind itself.
Furthermore, thermal energy contributes to the creation of wind. The atmosphere attempts to equalize global temperatures which can also cause air to move. As colder air is denser and tends to have higher pressure, it moves towards areas of lower pressure and warmer air. The Earth's rotation and friction at the surface affect the wind's speed and direction but are secondary influences compared to the horizontal pressure difference.