As Time Passed, Indentured Servitude Was Increasingly Replaced by African

As time passed, indentured servitude was increasingly replaced by African American slavery mainly because:

A) slaves were cheaper.
B) land owners found it difficult to communicate with the indentured servants.
C) economic conditions in England improved.
D) the slaves and land owners belonged to different cultures and religions.
E) the English preferred to deal with Africans, whom they could easily dominate.