Suppose Union Workers Are Earning More Than Similarly Qualified Nonunion

Suppose union workers are earning more than similarly qualified nonunion workers. From this, we can conclude that

A) unemployment of union workers must have increased.
B) unemployment of nonunion workers must have increased.
C) productivity of union workers must be greater than the productivity of nonunion workers.
D) Any of the above are possible and we cannot tell which without having more information.