Answer:
The best definition for Arkansas' Cooperationists is option B: those who were willing to wait and see what happened.
Cooperationists were a group of people in Arkansas who wanted to avoid secession from the United States and instead sought a compromise solution to the crisis of the 1860s. They believed in working with the federal government and other states to find a solution that would preserve the Union, rather than immediately seceding from it. While they were not necessarily opposed to slavery, they believed that the issue should not be the sole cause of secession.
Thus, Cooperationists were not people who immediately wanted to secede from the Union (option A), nor were they people who were willing to help their neighbors during time of war (option C). Option D is not a correct definition for Cooperationists as it describes a different group or idea.