Which, If Any, of the Following Statements Is True

Which, if any, of the following statements is true?

A) The heritability of a disease can vary from one human population to another, but remains fairly constant within any individual population.
B) The risk ratio in complex diseases is high compared to in monogenic disorders.
C) In complex diseases the concordance in phenotype between monozygotic twins is higher than between dizygotic twins
D) Disorders in which genetic factors have a large role always have a significantly higher concordance in phenotype between monozygotic twins and between dizygotic twins than do disorders where genetic factors play a less significant role.