Final answer:
The British supported a system of social rank based on skin color to legitimize slavery, maintain power, and reinforce white superiority.
Step-by-step explanation:
The most reasonable inference about why the British would support a system of social rank based on skin color is due to their colonial practices and the concept of racial superiority.
The British Empire, including its colonies in America, was built on the institution of slavery. By establishing a system of social rank based on skin color, the British could legitimize the enslavement and mistreatment of African people. This system allowed the British colonists to maintain control and power over the enslaved population, while also reinforcing their own sense of superiority.
Furthermore, the British justified their actions through pseudo-scientific theories of race and ideologies of white supremacy. These ideologies portrayed people of African descent as inferior and justified their subjugation as a natural hierarchy in society. The British also benefited economically from their control over enslaved people's labor and resources, which further incentivized their support for a system of social rank based on skin color.