Which Statement Below Explains the Uniform Width of the DNA

Which statement below explains the uniform width of the DNA molecule along its entire width?

A) A purine nitrogenous base always pairs with another purine nitrogenous base.
B) A pyrimidine nitrogenous base always pairs with another pyrimidine nitrogenous base.
C) A pyrimidine nitrogenous base always pairs with a purine nitrogenous base.
D) Repulsion between phosphate groups keeps the strands a uniform distance apart.
E) Attraction between phosphate groups keeps the strands a uniform distance apart.