Final answer:
In 1650, the Iroquois and Cherokee were among the Native American groups most affected by Europeans through conflicts and land acquisition. The Cherokee, in particular, faced significant pressures due to their acculturation and subsequent land acquisition by white settlers, eventually leading to the Trail of Tears.
Step-by-step explanation:
In 1650, the Native American groups that may have been most affected by Europeans were Iroquois-speaking people such as the Oneida and Seneca, whose lives were significantly impacted by European colonization. European contact altered the economy of the Native Americans and often forced them to take sides in European conflicts, resulting in significant shifts in their way of life. By the 1800s, many had migrated westward or were forcibly resettled. The introduction of European diseases like smallpox devastated Native American populations because they had no immunity to these diseases, impacting their ability to resist European expansion.
In the context of the provided options, however, the Cherokee might be the group most affected through land acquisition efforts by Europeans. This acquisition was driven in part by the Cherokee's acculturation to American society, which made their lands more desirable to white settlers. Ultimately, this culminated in the forced removal of the Cherokee during the Trail of Tears, where they were relocated from Georgia to Oklahoma.
Although the Sioux were engaged in the fur trade and may have been impacted economically by European contact, and the Navajo did experience livestock introduction which changed their agricultural practices, these impacts were not as immediate or as deeply felt in 1650 as the land pressures and eventual removal faced by the Cherokee.