Question

franchises are attractive to business owners because
they have a proven business model.
they are typically inexpensive to buy.
they get to keep all profits.
they come with very little risk.

Explanation:

Franchises are attractive to business owners because they operate under a proven business model. Buying a franchise is usually not inexpensive, franchisees do not keep all profits (they pay royalties/fees), and no business has "very little risk" (including franchises). So the correct reason is that they have a proven business model.

Answer:

A. they have a proven business model.