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.

Category: AMERICAN CITIES 
Clue: 6 of the top 10 U.S. cities in population are found in these 2 states
california & texas

Category: GOLF 
Clue: It's the only one of golf's 4 major pro events in which amateurs are not permitted to play
the pga championship

Category: AUTHORS 
Clue: In 1995 a library at the Glasgow Veterinary School was named in his honor

james herriot