Answer:
no one knows for sure but most think it was caused by WW2. When WWII started the USA started sending supplies to the allied powers and making the economy boom. When the USA entered the war millions of men where sent to the UK and all the jobs and factories where filled and pumping out supplies and resources at full swing.
If you meant France then it'd be B
A) Primary Source since that person experienced that event directly
Articles of Confederation. The Articles of Confederation and Perpetual Union was the first constitution of the United States.
