DNA and RNA contain four bases each. Which of the following bases in not present in RNA?

Options

A. Adenine
B. Uracil
C. Thymine
D. Cytosine

Explanation

To solve the question of which base is not present in RNA among the options given (adenine, uracil, thymine, and cytosine), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Composition of DNA and RNA**:
- DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are both nucleic acids composed of nucleotides. Each nucleotide consists of a nitrogenous base, a sugar, and a phosphate group.

2. **Identify the Bases in DNA and RNA**:
- The four nitrogenous bases found in DNA are:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)
- The four nitrogenous bases found in RNA are:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Uracil (U)

3. **Compare the Bases**:
- From the list above, we can see that RNA contains adenine, guanine, cytosine, and uracil.
- Thymine, which is present in DNA, is not found in RNA. Instead, thymine is replaced by uracil in RNA.

4. **Conclusion**:
- Therefore, the base that is not present in RNA from the provided options is **thymine**.

### Final Answer:
The base that is not present in RNA is **thymine**.

---