The structure that ruptures for dehiscence in moss capsule is

Options

A. Operculum
B. Annulus
C. Peristome
D. Calyptra.

Explanation

To solve the question regarding the structure that ruptures for dehiscence in a moss capsule, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the specific structure in a moss capsule that ruptures during the process of dehiscence, which is the release of spores.

2. **Identify the Structures**: In a moss capsule, there are several key structures:
- **Operculum**: This is the lid-like structure that covers the capsule.
- **Annulus**: This is a ring-like structure that connects the operculum to the theca (the spore-containing part of the capsule).
- **Peristome**: This is a structure that helps in the dispersal of spores.
- **Calyptra**: This is a cap-like structure that covers the developing capsule.

3. **Analyze the Function of Each Structure**:
- The **operculum** acts as a lid but does not rupture itself; it is lifted off during dehiscence.
- The **annulus** is crucial because it dries out and ruptures, allowing the operculum to detach from the theca.
- The **peristome** does not rupture; it is involved in the release of spores after dehiscence.
- The **calyptra** also does not play a role in the rupture during dehiscence.

4. **Determine the Correct Answer**: Based on the analysis, the structure that ruptures during dehiscence is the **annulus**. It is this structure that separates, allowing the operculum to be released and the spores to be dispersed.

5. **Final Conclusion**: The correct answer to the question is **option 2: annulus**.