Answer:
D. Both of them will be better off.
Step-by-step explanation:
In the voluntarily trade is a fair trade and in it both parties will finish being better off, meaning they will trade what they do not need for the thing they do need and that will help them off. Volunteer trade implies that no one is forced into labor or trade and that they had the freedom to sell or buy goods or services under their own terms.
In case one or both sides of the trade are damaged, the trade can't be considered volunteered or fair.