Read the following passage and mark the letter A, B, c, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42.

The first navigational lights in the New World were probably lanterns hung at harbor
entrances. The first lighthouse was put up by the Massachusetts Bay Colony In 1766 on Little Brewster Island at the entrance to Boston Harbor. Paid for and maintained by light dues levied on ships, the original beacon was blown up in 1776. By then there were only a dozen or so true lighthouses in the colonies. Little over a century later, there were 700 lighthouses.

The first eight erected on the West Coast in the 1850’s featured the same basic New
England design: a Cape Cod dwelling with the tower rising from the center or standing close by. In New England and elsewhere, though, lighthouses reflected a variety of architectural styles. Since most stations in the Northeast were built on rocky eminences, enormous towers were not the rule. Some were made of stone and brick, others of wood or metal. Some stood on pilings or stilts: some were fastened to rock with iron rods. Farther south, from Maryland through the Florida Keys, the coast was low and sandy. It was often necessary to build tall towers there – massive structures like the majestic Cape Hatteras, North Carolina lighthouse, which was lit in 1870. At 190 feet, it is the tallest brick lighthouse in the country.

Not withstanding differences in appearance and construction, most American lighthouses shared several features: a light, living quarters, and sometimes a bell (or, later, a foghorn). They also had something else in common: a keeper and, usually, the keeper's family. The keeper's essential task was trimming the lantern Nick in order to maintain a steady bright flame. The earliest keepers came from every walk of life-they were seamen. Farmers, mechanics, rough mill hands-and appointments were often handed out by local customs commissioners as political plums. After the administration of lighthouses was taken over in 1852 by the United States Lighthouse 803rd, an agency of the Treasury Department, the keeper corps gradually became highly professional.

In line 15, to which of the following does the word "They" refer?

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