If the Correlation Between Identical Twins on Trait R Is

Multiple Choice

If the correlation between identical twins on trait R is higher than is the correlation between fraternal twins on trait R, behaviour geneticists conclude that

A) genetic factors are important in the development of trait R.
B) genetic factors are irrelevant to the development of trait R.
C) environmental factors are irrelevant in the development of trait R.
D) genetic factors and environmental factors play equivalent roles in the development of trait R.