Question

read the paragraph, then choose the word that best completes the sentence. two underwater explorers have uncovered a mystery off the southern shore of lake ontario. in 2008, the pair found a rare nineteenth - century schooner, 500 feet (150 meters) beneath the surface. they did not expect to find the 55 - foot - long (17 - meter - long) boat. the two explorers were surveying the area when their equipment showed a faint image of something on the bottom. two weeks later, the explorers used an underwater vehicle to photograph the shipwreck. pictures revealed it to be a daggerboard schooner. this ship must have sunk in lake ontario more than 100 years before. however, there is no account of such an event. the schooner is a(n) ______ mystery. a industrial b international c scientific d historical

Explanation:

The schooner is a nineteenth - century vessel, and its sinking and discovery involve historical aspects. There's no indication of it being industrial, international, or primarily a scientific mystery in the given context.

Answer:

D. historical