This position was reached in a normal chess game:

                   BLACK
     +---+---+---+---+---+---+---+---+
     | B |///| K |/R/| N |///|   |///|  
     +---+---+---+---+---+---+---+---+
     |/P/| P |///|   |///|   |///|   |  
     +---+---+---+---+---+---+---+---+
     |   |///| Q |/K/|   |/R/|   |///|   
     +---+---+---+---+---+---+---+---+
     |///|   |///|   |///|   |///|   |
     +---+---+---+---+---+---+---+---+
     |   |///|   |///|   |///|   |///|
     +---+---+---+---+---+---+---+---+
     |///|   |///|   |///|   |///|   |
     +---+---+---+---+---+---+---+---+
     |   |///|   |///|   |///|   |///|
     +---+---+---+---+---+---+---+---+
     |///|   |///|   |///|   |///|   |
     +---+---+---+---+---+---+---+---+
                   WHITE

a) Identify the color of each piece.
b) What was the last move?