instruction:
You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
question:
Category: TELEVISION HISTORY 
Clue: Set in the 1870s, it ran from 1955 to 1975
answer:
gunsmoke


question:
Category: GEOGRAPHY NEWS 
Clue: On the initiative of Sen. Patrick Leahy, in 1998 it was designated the sixth Great Lake
answer:
lake champlain


question:
Category: THE 1980S 
Clue: On Dec. 20, 1989 President Bush sent about 10,000 troops into this country as part of Operation Just Cause
answer:

panama