50. Which of the following is true of the fourth paragraph? (A) There are more lighthouses in the United States now than there were in 1900. (B) There are more lighthouses in the United States today than in any other country. (C) There are more functioning lighthouses in the United States today than there are lighthouses preserved as historical monuments. (D) There were more lighthouses in the United States in 1900 than there are elsewhere in the world today.