GMAT question Part 2

In a backgammon match, a win counts for 1 point, a loss counts for 0 points and a draw counts for 0.5 point. After 15 games, the winner was four points ahead of the loser. How many points did the loser have?

A. 9
B. 6
C. 5.5
D. 4.5
E. 7