Which of the Following Statements Is True

Which of the following statements is true?

A) To deny the existence of biological race is not to deny the existence of human biological or genetic diversity.
B) Clines overlap with racial categories discovered in the nineteenth century.
C) Clinal mapping shows that patterns of human diversity can be usefully sorted into a handful of mutually exclusive categories.
D) Macroevolutionary studies carried out after World War II made the study of within-species variation possible.