Which of the following was not an effect of westward expansion?

The choice indicating that Native Americans learned new techniques of irrigation is correct in this context because, while some adaptation to new agricultural practices may have occurred in specific instances, the broader and more significant impacts of westward expansion were detrimental to Native American tribes. The movement westwards led to the confinement of these tribes on reservations, often resulting in loss of culture and traditional practices. Furthermore, diseases brought by settlers caused widespread fatalities among Native populations, and resource depletion was another significant consequence of the influx of settlers, who often mismanaged the land and its resources. In this context, the statement about learning new irrigation techniques does not capture the overall negative effects of westward expansion on Native American communities.