Choose the word (A, B, C or D) that best fits the blank space in the following passage: Alexander Graham Bell, the American (1) ……… and teacher of the deaf, was most famous (2) ……… his invention of the telephone. He was born on March 3, 1847, in Edinburgh, Scotland and educated at the universities of Edinburgh and London. He (3) ……… to Canada in 1870 and to the United states in 1871. In the United States he began teaching deaf mutes, publicizing the system called visible (4) ……… The system, which was developed by his father, the Scottish educator Alexander Melville Bell, shows (5) ……… the lips, tongue and throat are used in the articulation of sound. In 1872 Bell founded a school for deaf – mutes in Boston, Massachusetts. The school subsequently became part of Boston University, (6) ……… Bell was appointed professor of vocal physiology. He became a naturalized U.S citizen in 1882.