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 1716 on Little Brewster Island at the entrance to Boston Harbor. Paid for and maintained by "light dues" levied (征收) on ships, the original beacon was blown up in 1776. Until then there were only a dozen or so true lighthouse in the colonies. Little over a century later, there were 700 lighthouses.
The first eight lanterns 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 set up on rocky eminences (高处), enormous towers were not the rule.
Some of them were made of stone and brick, others of wood or metal. Some of them stood on pilings or stilts; others 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 structure 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.
Notwithstanding differences in appearenced construction, most lighthouses in America shared several features: a light, living quarters, and sometimes a bell (or, later a foghorn). They also had quarters, and something else in common: a keeper and, usually, the keeper’s family. The keeper’s essential task was trimming the lantern wick (灯芯) in order to maintain a steady, bright flame. The earliest keepers came from every industry— they were seaman, farmers, mechanics, rough mill hands—and appointments were often handed out by local customs commissioners as political plums. After the administration of lighthouse was taken over in 1852 by the United States Lighthouse Board, and agency of the Treasury Department, the keeper corps gradually became highly professional.
It can be inferred from the passage that the Treasury Department, after assuming control of the lighthouse, improved which of the following()
A．The training of the lighthouse keepers.
B．The sturdiness of the lighthouses.
C．The visibility of the lights.
D．The locations of the lighthouses.
