Select the correct pairing .

Options

A. Heart wall - Involuntary unstriated muscle
B. Biceps of the upper arm - Voluntary unstriated muscle
C. Abdominal wall - Involuntary striated muscle
D. lris - Involuntary unstriated muscle

Answer

To solve the question regarding the correct pairing of muscle types and their characteristics, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understand Muscle Types**:
- There are three main types of muscles in the human body: skeletal, smooth, and cardiac.
- **Skeletal Muscles**: Striated (striped), voluntary (under conscious control), attached to bones (e.g., biceps).
- **Smooth Muscles**: Non-striated (not striped), involuntary (not under conscious control), found in organs (e.g., stomach, intestines).
- **Cardiac Muscles**: Striated, involuntary, found only in the heart.

2. **Evaluate Each Option**:
- **Option A**: Heart wall - involuntary unstriated muscles.
- **Analysis**: The heart wall contains cardiac muscles, which are striated, not unstriated. This option is incorrect.

- **Option B**: Biceps of the upper arm - voluntary unstriated muscles.
- **Analysis**: The biceps are skeletal muscles, which are striated, not unstriated. This option is incorrect.

- **Option C**: Abdominal wall - involuntary striated muscles.
- **Analysis**: The abdominal wall contains smooth muscles, which are non-striated. This option is incorrect.

- **Option D**: Iris - involuntary unstriated muscles.
- **Analysis**: The iris contains smooth muscles, which are indeed involuntary and unstriated. This option is correct.

3. **Conclusion**:
- After analyzing all options, the correct pairing is **Option D: Iris - involuntary unstriated muscles**.

### Final Answer:
The correct pairing is **D: Iris - involuntary unstriated muscles**.