Answer:
[tex]\boxed {\tt Uracil}[/tex]
Explanation:
The nitrogenous bases in deoxyribonucleic acid, or DNA are:
The nitrogenous bases in ribonucleic acid, or RNA are:
When we compare the lists, we notice that RNA contains uracil instead of the thymine in DNA. Therefore, the correct answer is B. Uracil