Twins are said to be concordant for a trait when

Twins are said to be concordant for a trait when
  A. both twins exhibit the trait.
  B. only identical twins exhibit the trait.
  C. only fraternal twins exhibit the trait.
  D. fraternal twins more often show the trait than identical twins.
  E. None of these is true.

Question 2

In a certain population with a mean IQ of 100, the heritability of IQ was measured at 0.6. A chapter of
  Mensa in this population has an average IQ of 140. If they are otherwise typical of their population,
  about how many of their IQ points can be attributed to their genes?
  A. 60
  B. 84
  C. 24
  D. 100
  E. 40