C stands for cytosine
Cytosine is one of the nitrogenous bases that form part of a nucleotide. In nature , there are five types of bases namely adenine, thymine, guanine and cytosine and uracil.
In the structure of DNA, there are found these bases with the exception of uracil which is never found in DNA but in RNA. In RNA, the base thymine has been replaced with uracil.
These bases pair with each other according to base pairing rule and this is that in DNA, adenine always pairs with Thymine and Guanine with cytosine. In RNA it is the same thing with the exception of adenine which pairs with uracil.
T