Which of the following is true for American options?

A. Put-call parity provides an upper and a lower bound for the difference between call and put prices
B. Put call parity provides an upper bound but no lower bound for the difference between call and put prices
C. Put call parity provides a lower bound but no upper bound for the difference between call and put prices
D. There are no put-call parity results

A

Put call parity provides both an upper and a lower bound for the difference between call and put prices. See equation (11.11).