If a country joined an economic union (for example, the European Union) its business sector could benefit from all of the following except which one?

If a country joined an economic union (for example, the European Union) its business sector could benefit from all of the following except which one?
A . Higher profit margins due to a reduction in transport costs.
B . Economies of scale as it gained access to a larger market.
C . Lower input costs as imports from other member states would become cheaper.
D . Reduced costs as a result of access to a wider supply of factors of production.

Answer: A