A complete pit is

Options

A. Depression in secondary wall
B. Pit chamber and primary wall
C. Pit chambers of two adjacent cells and pit membrane
D. Pit chamber, primary wall and middle lamella

Answer

### Step-by-Step Solution

1. **Understanding the Concept of a Pit**:
A pit is a small opening or depression in the cell wall that allows for communication and fluid exchange between adjacent cells. It is crucial for cellular interactions.

**Hint**: Remember that pits are essential for cell communication.

2. **Identifying Components of a Complete Pit**:
A complete pit consists of three main components:
- **Pit Chamber**: The hollow area that connects two adjacent cells.
- **Pit Membrane**: A thin layer that separates the pit chamber from the external environment, which includes parts of the primary wall and middle lamella.
- **Pit Apparatus**: The structure that includes the secondary wall surrounding the pit chamber.

**Hint**: Think of the complete pit as a structure with a chamber, a membrane, and an apparatus.

3. **Analyzing the Options**:
The options provided in the question are:
- Option 1: Depression and secondary wall
- Option 2: Pit chamber and primary wall
- Option 3: Pit chamber of two adjacent cells and pit membrane
- Option 4: Pit chamber, primary wall, and middle lamella

Among these options, we need to find which one correctly describes a complete pit.

**Hint**: Look for the option that includes both the pit chamber and the membrane.

4. **Selecting the Correct Option**:
The correct option is **Option 3**: "Pit chamber of two adjacent cells and pit membrane." This option accurately describes the components of a complete pit, as it highlights the connection between two cells and includes the necessary membrane.

**Hint**: Focus on the relationship between adjacent cells when choosing the correct option.

5. **Conclusion**:
A complete pit is defined by its three components: the pit chamber, the pit membrane, and the pit apparatus. The correct answer to the question is Option 3, which encompasses the essential elements of a complete pit.

**Hint**: Remember that understanding the structure helps in identifying the correct components.