Which of the following base is not present in RNA ?

Options

A. adenin
B. uracil
C. thymine
D. cytosine

Answer

To determine which base is not present in RNA, we need to analyze the bases that are typically found in RNA compared to those found in DNA.

### Step-by-Step Solution:

1. **Identify the Bases in RNA**:
RNA (ribonucleic acid) contains four nitrogenous bases:
- Adenine (A)
- Uracil (U)
- Cytosine (C)
- Guanine (G)

2. **Identify the Bases in DNA**:
DNA (deoxyribonucleic acid) contains four nitrogenous bases:
- Adenine (A)
- Thymine (T)
- Cytosine (C)
- Guanine (G)

3. **Compare the Bases**:
From the lists above, we can see that:
- Adenine (A) is present in both RNA and DNA.
- Uracil (U) is unique to RNA and replaces Thymine (T) found in DNA.
- Cytosine (C) is present in both RNA and DNA.
- Thymine (T) is not present in RNA.

4. **Conclusion**:
The base that is not present in RNA is Thymine (T).

### Final Answer:
Thymine (Option C) is not present in RNA.

---