A DNA molecule is composed of two polynucleotide strands. Which description is correct?
- AThe percentage of cytosine is $50\%$ of that of guanine in the whole molecule.
- BThe percentage of cytosine is the same as that of guanine in each strand.
- CThe percentage of cytosine is the same as that of guanine in the whole molecule.
- DThe percentage of cytosine is the same in each strand of the molecule.