Which of the following statement is CORRECT about a firm's shutdown condition?

	a.	A firm should shut down its operation when its economic profit is zero.
	b.	The critically low market price at which revenue just equal fixed cost is called the shutdown point.
	c.	A firm should shut down its operation when the market price is exactly the same as its minimum average cost.
	d.	The critically low market price at which losses exactly equal fixed cost is called the shutdown point.