A swift current occurring in a narrow passage connecting two large bodies of water, which is produced by the continuously changing difference in height of tide at the two ends of the passage, is called a __________.

Correct Answer: Option A — hydraulic current

As detailed in Bowditch, a hydraulic current is generated by a continually changing difference in tidal height between two distinct water bodies connected by a narrow channel. Water flows rapidly from the higher body to the lower body until the levels equalize.