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: TO REMAIN "SILENT" 
Clue: Quiet alliterative nickname of the U.S. Navy's submarine fleet
the silent service

Category: LIBRARIES 
Clue: Samuel Pepys' famous diary is housed at the Pepysian Library at Magdalene College at this university
cambridge

Category: ANATOMY 
Clue: The human body has 3 types of these: skeletal, smooth & cardiac, a combination of skeletal & smooth

muscles