Jamal has a drawer containing 6 green socks, 18 purple socks, and 12 orange socks. After adding more purple socks, Jamal noticed that there is now a 60\% chance that a sock randomly selected from the drawer is purple. How many purple socks did Jamal add?
Answer Choices
A. 6
B. 9
C. 12
D. 18
E. 24