In 1786, a group of western Massachusetts farmers rose up to protest taxes and actions against debtors. This uprising, known as Shays' Rebellion, was important because it -

a
showed that the Confederation Congress was too weak to tax farmers
b
demonstrated the national government's lack of power to regulate interstate commerce (business from state to state)
c
revealed the inability of the national government to put down an uprising
d
exposed the need for states to have votes in Congress based on their size