Which of the following statements concerning payback analysis is true?

	a.	If all other variables are the same, an investment with a shorter payback period is preferable to an investment with a longer payback period.
	b.	The payback method ignores the time value of money concept
	c.	The payback method and the unadjusted rate of return are different approaches that consistently lead to the same conclusion.
	d.	a and b