Because they believed the Manchos Dynasty had lost the Mandate of Heaven.
(Sorry if I'm wrong)
The answer to this open question is the following.
You forgot to include the options for this question. However, we can comment on the following, in general terms.
What contributed most to the increasing use of African slave labor in
North America during the 1600s and 1700s was the constant demand of more hands, more labor workers to work in the large plantations of the North American colonies.
At the beginning of the colonial settlings, most colonies used indentured servitude. But the need for more hands made plantation owners import African slaves to grow crops such as cotton, tobacco, and rice. Southern plantations depended too much on slaves because landlords had to export crops to Europe.
The main cause is culture and religion. hope this helps
