Question: How many HC climbs had 1 visit more recently than 1984, a first HC climb before 1994, and a height of 1900?
SQL: SELECT no_of_hc_climbs FROM table_name_35 WHERE no_of_times_visited = 1 AND most_recent > 1984 AND first_time_as_hc_climb < 1994 AND height__m_ = "1900"