Thomas Jefferson explanation because he wrote most of the deceleration of independence and had some changes to get approved (: hope this helps
In both cultures, the basis of their economy was agriculture. But this was very difficult to carry out due to the geographical conditions in which they were. They were located in an area where the climate was very dry, the land was scarce and there was very little water to irrigate those lands. Both Chavin and Nazca solved this by using underground aqueducts to transport water and, therefore, irrigate the crops permanently. Then, the most important reason why they resorted to this mechanism is the lack of water to irrigate the crops.
A historian would first look at the reliability of a source - when it was published and what was happening at the time (context), who wrote it and their qualifications, any bias the author may hold, whether author sources corroborate the source, whether the author has used references, whether the source provides evidence, who the source is representative of and whether the source provides a balanced perspective
