45. __________ At first, people along the coast burned huge wood fires out in the open. Later on, lighthouses were built, first burning wood, then coal. They signaled to ships that they were close to the land. The flames made very bright warning beacons at night. Today, special electric lamps send out powerful beams to warn faraway ships of danger. (A) Lightships are positioned where lighthouses are impossible to erect. (B) There are three types of lighthouses: those on the coast, those on offshore reefs, or those on sandbanks. (C) Lighthouses, towers carrying lights that guide ships to land, are tourist attractions. (D) Lighthouses have changed since sailors first began looking toward land for warning signals.