You start a search for a buried object by marking the center of a field as (0,0), with coordinates giving distances in yards. Coordinates to the north or east are positive, and coordinates to the south and what are negative. You find nothing at (-10 , 6), so you try a likely looking spot 3 yards to the east and 13 yards to the south of the first spot. What are the coordinates of the second spot?
A: (-7, -6)
B: (12, -6)
C: (-13, -9)
D: (5, -3)