Which of the following statements are true/false:

I: The implied volatility of a stock can be calculated by deternining the standard deviation of stock returns over the last one year.

II: The implied volatility of a stock can be calculated by deternining the standard deviation of stock returns over the last six months.

	A.	I is true, II is false
	B.	I is false, II is true
	C.	I and II are both false
	D.	I and II are both true