DNA and RNA have three important structural differences. These include all of the following EXCEPT that __________.
A. in living cells, DNA is usually a double-stranded molecule while RNA can often be single-stranded
B. DNA contains deoxyribose while RNA contains the sugar ribose
C. DNA contains phosphate while RNA does not
D. DNA contains the bases A, G, C, and T while RNA contains the bases A, G, C, and U