The belief behind Manifest Destiny was rooted in the idea that American settlers were destined to expand across North America, which often included the belief that this expansion was not only justified but also beneficial. The ideology was primarily centered on the notion that American culture and democracy were superior and that it was the nation's divine right to spread its values across the continent.
Among the options provided, none directly encapsulate the core belief of Manifest Destiny. However, the closest fit, albeit with nuance, would be the notion that "Native Americans would benefit from the introduction of the settlers’ American way of life." This reflects the paternalistic view that many proponents of Manifest Destiny held, though it overlooks the significant negative impacts on Native Americans and their cultures that this expansion caused.
Still, it's essential to recognize that Manifest Destiny was largely ethnocentric and ignored the rights and sovereignty of Native Americans.