Final answer:
Pioneer trails and settlers traveling them negatively affected Native Americans by introducing diseases they had no immunity to, disrupting their way of life, and leading to conflicts and forced removals onto reservations. The correct option is D. brought diseases west
Step-by-step explanation:
Pioneer trails and the settlers who traveled them negatively affected American Indians in several ways. One of the major impacts was the introduction of diseases for which the Native Americans had no natural immunity. As Europeans traveled westward, they unknowingly brought disease-causing bacteria and viruses, which resulted in devastating epidemics among Native American populations. It is estimated that up to 90 percent of Native Americans died from infectious diseases after the arrival of Europeans.
Additionally, the settlers' encroachment on Native American lands disrupted their way of life. The settlers' actions, such as the destruction of buffalo migration patterns and the confinement of Native Americans to reservations, had a negative impact on their ability to hunt, gather resources, and maintain their traditional lifestyles.
Furthermore, the settlers' greed for land and resources often led to conflicts with Native American tribes. This resulted in violence between the United States and Native American nations, ultimately leading to the forced removal of tribes onto reservations and the transformation of tribal cultures. The correct option is D. brought diseases west