Suppose you invest $20,000 by purchasing 200 shares of Abbott Labs (ABT) at $50 per share, 200 shares of Lowes (LOW) at $30 per share, and 100 shares of Ball Corporation (BLL) at $40 per share. Over the next year Ball has a return of 12.5%, Lowes has a return of 20%, and Abbott Labs has a return of -10%. The value of your portfolio at the end of the year is:

A: $21,500

B: $20,000

C: $21,000

D: $20,700