What is the proper economic for money that is available for investment

The proper economic term for money that is available for investment is A. "capital," or even more properly, "financial capital." It's not a dividend, because that's the money that a company pays to shareholders. It's not shares, because those are the stocks that you already own. So, given that it is money, financial capital would be the correct answer, because it has to do with money, whereas economic one doesn't.