Which of the following is present in both plant and animal cells?

Options

A. Primary wall
B. Secondary wall
C. Plasma membrane
D. Plastids

Answer

To determine which of the following structures is present in both plant and animal cells, we can analyze each option provided:

1. **Primary Wall**:
- The primary wall is a component of the cell wall, which is found only in plant cells. Therefore, this option is not correct.

2. **Secondary Wall**:
- Similar to the primary wall, the secondary wall is also part of the cell wall and is exclusive to plant cells. Thus, this option is also incorrect.

3. **Plasma Membrane**:
- The plasma membrane, also known as the cell membrane, is present in all living cells, including both plant and animal cells. In plants, the plasma membrane is located just inside the cell wall, while in animal cells, it is the outermost boundary. This option is correct.

4. **Plastid**:
- Plastids are double-membrane organelles that are primarily involved in photosynthesis and are found only in plant cells and some algae. Therefore, this option is not correct.

Based on the analysis, the correct answer is the **Plasma Membrane**, as it is the only structure that is present in both plant and animal cells.

### Summary of the Steps:
1. Analyze the **Primary Wall** - exclusive to plant cells.
2. Analyze the **Secondary Wall** - also exclusive to plant cells.
3. Analyze the **Plasma Membrane** - present in both plant and animal cells.
4. Analyze the **Plastid** - exclusive to plant cells and some algae.