Final answer:
Reconstruction took place from 1865 to 1877, not until 1890, so the statement is false. The division of the South into military districts in 1867 under the First Reconstruction Act is true. Cotton remained a vital economic element in the South during this time.
Step-by-step explanation:
The statement that Reconstruction took place from 1865 to 1890 is false. The formal period of Reconstruction began at the end of the Civil War in 1865 and lasted until the withdrawal of the U.S. Army from the former Confederate States on March 31, 1877. Additionally, according to the First Reconstruction Act passed in 1867, it is true that the South was divided into military districts. This was one of the key measures taken to establish order and governance in the post-war South. Historical evidence confirms that cotton remained an economic cornerstone for the South during this period, so the statement that cotton formed a strong economic basis for the South during Reconstruction is true.