There are some projects with their financial information, which option is the best candidate for your portfolio? (we like to have our initial investment returns in less than 4 years)

	a.	BCR=0.5, ROI=20%, payback period=2 years
	b.	BCR=3, ROI=15%, payback period=3.2 years
	c.	BCR=3.5, ROI=25%, payback period=1.8 years
	d.	BCR=4, ROI=10%, payback period=4.5 years