题目内容：
根据短文，回答题
Which of the following was true of the slavery in America?
[ A ] The colonists sold African Americans to planters in the Caribbean.
[ B ] Native American slaves performed agricultural labor.
[ C ] During the 17th century, the white indentured servitude was the main labor in the Southern colonies.
[ D ] It was at the end of the 17th century that African people began to be brought to America.
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