Which of the following statements is correct?

	a.	Assume that you own a put option on a stock, and the option matures today. The current stock price is $70, and the exercise price is $60. Then, you exercise the option.
	b.	Underlying assets of American options are U.S. companies.
	c.	When a firm is unable to pay off outstanding debt, common stockholders have obligation to pay off the debt on behalf of the firm.
	d.	You have sold (i.e. written) a call option with the exercise price of $70. The underlying stock price is $100 on the maturity date. You make a profit of $30 from the transaction.
	e.	European call option is the right to buy a specified asset at a specified price on the maturity date.