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.

Q: Category: THE TITANIC 
Clue: When the RMS Titanic sank in 1912, its cargo included more than 7 million pieces of this, in some 3,400 sacks

A: mail
****
Q: Category: ROMAN EMPERORS 
Clue: In 59 A.D. Agrippina wrote to this man, her son, "Tell me why I should plot against your life?"--she was killed anyway

A: nero
****
Q: Category: AFRICA 
Clue: In November 2005 leaders of Spain & France joined in celebrating the 50th anniversary of this country's independence

A:
morocco
****