The correct answer is C) when families have extra food.
A food surplus is a benefit of farming. A food surplus is when families have extra food.
The term "surplus" means that there is an excess of production of something. In this case, food. Ther is extra food for people to consume. And that is good for families.
In business, a surplus means that a company had extra production and has more products to sell that could represent a better income for the company.
