The Fact That Children in Different Cultures _____ in the Age

The fact that children in different cultures _____ in the age at which basic motor skills appear demonstrates that _____.

A) vary somewhat; genetic factors can slow or accelerate early motor development
B) vary somewhat; environmental factors can slow or accelerate early motor development
C) do not vary; genetic factors alone determine early motor development
D) do not vary; environmental factors have little impact on early motor development