The Early Status of Blacks in North America Under the British

The early status of blacks in North America under the British colonies was initially unfree, but they were not slaves. Why was this so?

A) Unlike Spain and Portugal, England had no legal experience with slavery, and had no codes to guide them.
B) The British were intent on converting the pagan Africans to Christianity.
C) The first arrivals had been stolen from the Spanish, and British common law required that they be set free immediately.
D) All of these are correct.