An instrument that maintains a continuous record of humidity changes is called a __________.

Correct Answer: Option B — hygrograph

A hygrograph is a specialized recording hygrometer that utilizes a hair element or similar sensor to track and graph relative humidity over time. Per Bowditch, this continuous record is essential for meteorological monitoring, distinguishing it from a thermometer (temperature), barometer (pressure), or simple hygrometer which only provides instantaneous readings.