ANS:D - all of the above.

Atmospheric pressure varies with altitude, temperature, and weather conditions.

1. Altitude: Atmospheric pressure decreases with increasing altitude. As you go higher in the atmosphere, the air becomes less dense, leading to lower atmospheric pressure.
2. Temperature: Atmospheric pressure also varies with temperature. Warmer air tends to be less dense, causing lower pressure, while cooler air is denser and leads to higher pressure.
3. Weather Conditions: Weather systems, such as high and low-pressure systems, fronts, and storms, can cause temporary changes in atmospheric pressure. For example, low-pressure systems are associated with stormy weather and have lower atmospheric pressure compared to high-pressure systems, which are associated with fair weather and higher atmospheric pressure.