Question 869Navigation General

The correct answer is D) Barometer. A barometer is the instrument used to measure atmospheric pressure and predict the approach of low pressure systems. Low pressure systems are typically associated with stormy weather, so monitoring changes in barometric pressure is an important tool for mariners to anticipate the arrival of approaching storms. The other answer choices are incorrect because: An anemometer measures wind speed, a fathometer measures water depth, and a thermometer measures air temperature - none of which are directly used to predict low pressure systems.