Which type of RNA includes uracil instead of thymine?

The correct answer is mRNA. In RNA (Ribonucleic Acid), the nitrogenous base uracil is used in place of thymine, which is found in DNA (Deoxyribonucleic Acid). In mRNA, uracil pairs with adenine during the process of transcription. This is a fundamental characteristic of all RNA molecules, differentiating them from DNA.

While tRNA and rRNA also contain uracil instead of thymine in their structures, the question specifically highlights which type of RNA is most commonly associated with this fact. mRNA is often the focus when discussing the role of uracil because it serves as the primary template for protein synthesis in the process of translation.

Thus, while it's true that tRNA and rRNA also utilize uracil, mRNA is frequently emphasized in educational contexts regarding RNA structure and function, making it a suitable response in this scenario.