You are given the following information about American options on a stock:

• The current stock price is 72.

• The strike price of the options is 80.

• The continuously compounded risk-free rate is 5%.

• Time to expiration is 1 year.

• Every six months, the stock price either increases by 25% or decreases by 15%.

Using a two-period binomial tree, calculate the price of an American put option.

(A) Less than 8

(B) At least 8, but less than 9

(C) At least 9, but less than 10

(D) At least 10, but less than 11

(E) At least 11