The current price of a non-dividend paying stock is ¥50. Use a two-step tree to value an American put option on the stock with a strike price of ¥48 that expires in 12 months. Each step is 6 months, the risk free rate is 5% per annum, and the volatility is 20%.  Which of the following is the option price?

A、
¥1.95
B、¥2.00
C、¥2.05
D、¥2.10