One of the problems unions are experiencing today is the reluctance of autoworkers
in southeastern United States to join unions. In a few instances, when the Auto
Workers Union (AUW) gathered enough employee signatures to call for a(n)
election, the employees have voted against unionization.

One drawback of voluntary trade is that it a. requires two groups to use a common language b. can make one group dependent upon another for necessary goods c. doesn't occur unless there is a shortage of goods for at least one group d. forces groups to rely on themselves to produce all the goods they need