Which of the Following Sources of Variation Is Not Taken

Multiple Choice

Which of the following sources of variation is not taken into account by a twin study design?

A) variation attributable to genetic factors
B) variation attributable to other factors, such as unique individual experiences
C) variation due to a shared family environment among those reared together
D) none of these sources of variation are taken into account by a twin study design
E) all of these sources of variation could be taken into account by a twin study design