A young couple living in rural west-central Missouri heard about the closing of a local grocery store. Although a small operation, it served a small community that would now have to travel another 20 miles to the nearest grocery store. With help from a local realtor and banker, the couple purchased the store, remodeled it, and re-opened it. As new storeowners, they had to carefully watch cash flow. As their customer base began to grow, they began offering hot food, and hired others to help with the operation. The economic benefit created in this story is called:

Invisible hand is an economic term used to describe the unexpected benefits to a business venture who acted in self benefits, but there is a great benefit in such business.

This, clearly leads to the benefit which was unexpected in the business.

In the given instance also, the couple occupied the business but, the benefits were completely unexpected and the growth rate is also high as related o investment rate.

Thus, the correct phrase for such situation is:

An Invisible Hand.