Why Do the Authors of the Textbook Not Support the Belief

Why do the authors of the textbook not support the belief that it is scientifically useful to connect human "races" and behavior?

A) Their research concluded that most behaviors showed no difference between supposed "racial" groups.
B) The connection between "race" and behavior is intangible and unsuitable for scientific study.
C) There is not enough cultural data available to create a good study sample
D) The authors believe that it makes more sense to connect "races" with emotions than with behaviors.