What is the difference between internal growth rate and sustainable growth rate?

	a.	Internal growth rate indicates the maximum growth that can be achieved by using only retained earnings, whereas sustainable growth rate indicates the maximum growth that can be achieved without external financing.
	b.	Internal growth rate indicates the maximum growth that can be achieved by maintaining constant debt ratio, whereas sustainable growth rate indicates the maximum growth that can be achieved by using only retained earnings.
	c.	Internal growth rate indicates the maximum growth that can be achieved without external financing, whereas sustainable growth rate indicates the maximum growth that can be achieved by using only retained earnings.
	d.	Internal growth rate indicates the maximum growth that can be achieved by using only retained earnings, whereas sustainable growth rate indicates the maximum growth that can be achieved by maintaining constant debt ratio.
	e.	None of the above