Question 778Navigation General

The correct answer is B) barometer. The passing of a low pressure system can be determined by periodically checking the barometer, which measures atmospheric pressure. As a low pressure system moves through an area, the barometer will show a steady decrease in pressure, indicating the approach and passage of the low pressure system. The other options are incorrect because they measure different weather parameters - a thermometer measures temperature, a hygrometer measures humidity, and an anemometer measures wind speed. While these instruments provide valuable weather information, they do not directly indicate the passage of a low pressure system like a barometer does.