A Total of 1,500 Pairs of Adult Twins,600 Monozygotic and 900

A total of 1,500 pairs of adult twins,600 monozygotic and 900 dizygotic,were studied to estimate the concordance for a childhood cancer.In the 600 monozygotic twins,40 of the pairs were concordant for the disease,60 of the pairs were discordant for the disease,and neither twin had the disease in the remaining 500 pairs.In the 900 dizygotic twins,30 of the pairs were concordant for the disease,120 of the pairs were discordant for the disease,and neither twin had the disease in the remaining 750 pairs.What is the discordance rate,in dizygotic twins,of the disease in twin pairs with at least one affected member?

A) 0.1
B) 0.2
C) 0.6
D) 0.8
E) 1.5