What is a simple definition for Return on Investment or ROI?

A.
how much incremental profit or cost savings is realized for a given use of money.

B.
how much profit is increased by investing in a specific asset.

C.
how long it will take to recover the investment from increased business value.

D.
how does the investment measure against the profits of the business.

Explanation:
Reference:http://searchcio.techtarget.com/definition/ROI(first paragraph)