If the initial amount of DNA is denoted as 2C then the amount of DNA after S-phase will be:

Options

A. 4 C
B. 6 C
C. C
D. 2 C

Answer

To solve the question regarding the amount of DNA after the S-phase when the initial amount is denoted as 2C, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Initial Amount of DNA**:
- The initial amount of DNA is given as 2C. Here, "C" represents the basic unit of DNA content in a cell.

2. **Identify the Stages of the Cell Cycle**:
- The cell cycle consists of two main phases: Interphase and M phase. Interphase is further divided into three stages: G1, S, and G2. The S-phase is specifically responsible for DNA replication.

3. **Focus on the S-phase**:
- During the S-phase, DNA replication occurs. This means that each chromosome is duplicated, resulting in the formation of sister chromatids.

4. **Determine the Change in DNA Content**:
- Before the S-phase, the cell has 2C of DNA. After the S-phase, each chromosome has been replicated. Therefore, the total amount of DNA doubles.

5. **Calculate the Amount of DNA After S-phase**:
- If the initial amount of DNA is 2C, after replication during the S-phase, the amount of DNA will be:
\[ \text{Amount of DNA after S-phase} = 2C \times 2 = 4C. \]

6. **Conclusion**:
- Thus, the amount of DNA after the S-phase will be 4C.

### Final Answer:
The amount of DNA after S-phase will be **4C**.

---