One reason the US Constitution was adapted instead of the Articles of Confederation was because D) Shay's Rebellion revealed the weaknesses of the Articles of Confederation.
The Articles of Confederation, America's first constitution, was extremely ineffective. Due to fear of a tyrannical central government, the Americans made a system where the state governments have almost all the power and the central government had very little. This was shown in Shay's Rebellion, as the federal government could not raise an army to stop it from happening.
As for the second question, the accomplishment that would complete the chart would be All of the former Confederate states were readmitted to the Union.