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: EXPLORERS 
Clue: John Speke died just before he was to debate this former exploring partner on the source of the Nile
sir richard burton

Category: & NEVER THE TWAINS SHALL MEET 
Clue: Shania's self-titled debut went gold in 1996; in 1873 Mark's first novel had this "golden"-sounding title
the gilded age

Category: MYTHOLOGY 
Clue: The most important Roman god next to Jupiter; in fact, it is next to Jupiter

mars