A mercurial barometer at sea is subject to rapid variations in height ("pumping") due to the pitch and roll of the vessel. To avoid this error, measurements of atmospheric pressure at sea are usually measured with a(n) __________.

Correct Answer: Option A — aneroid barometer

Aneroid barometers utilize a flexible metal bellows rather than a liquid column, making them immune to the mechanical oscillations caused by a vessel's pitch and roll. This design provides a stable, accurate reading of atmospheric pressure at sea, whereas mercurial barometers suffer from significant pumping errors due to motion.