Concept:A trade association is a voluntary body of businesses in the same industry, formed to safeguard their shared welfare.
Explanation:Businesses engaged in the same or similar trade come together to form these associations.
They operate on a non-profit basis and are independent voluntarily.
Their main goal is to promote and protect the common interests of all members.
This includes improving industry conditions and assisting members without taking away their right to make essential managerial decisions.
Associations are not focused on a single product, the general market, or only customers.
Instead, they work cooperatively to advance the collective business interests of the group.
Answer:B. common interest.