Which one of the following weather conditions indicates a sudden fall in barometer reading ?

A barometer measures atmospheric pressure, and its readings are a primary tool for weather forecasting. A sudden or rapid fall in barometric pressure indicates the approach of a low-pressure system or depression [2]. Such a drop is a strong indicator of approaching inclement or stormy weather, as lower pressure is associated with rising air, cloud formation, and precipitation [2]. Specifically, in maritime contexts, a swift fall in pressure (such as 3 mb or more below the mean) is a critical warning sign of a brewing Tropical Revolving Storm (TRS) or cyclone. Conversely, high or rising barometric pressure typically signifies fair, tranquil, or clear weather conditions [2]. Therefore, a sudden fall in the barometer reading is most characteristically associated with stormy weather, while calm or sunny weather is linked to stable or rising pressure levels.

Sources

1. [2] https://www.weather.gov/source/zhu/ZHU_Training_Page/winds/pressure_winds/Pressure.htm