Main proteins of striated muscles are

Options

A. Actin
B. Myosin and tropomyosin
C. Troponin
D. All of these

Answer

### Step-by-Step Solution:

1. **Identify the Types of Striated Muscles**:
Striated muscles consist of two main types: skeletal muscles and cardiac muscles. Both types are involved in voluntary and involuntary movements, respectively.

2. **Understand the Function of Striated Muscles**:
The primary function of striated muscles is to generate force and facilitate contraction. This contraction is crucial for various bodily functions such as locomotion, respiration, and maintaining posture.

3. **Identify the Main Proteins in Striated Muscles**:
The main proteins found in striated muscles include:
- **Actin**: A protein that forms thin filaments and is essential for muscle contraction.
- **Myosin**: A protein that forms thick filaments and interacts with actin to produce muscle contraction.
- **Tropomyosin**: A regulatory protein that binds to actin and helps regulate muscle contraction.
- **Troponin**: Another regulatory protein that works with tropomyosin to control the interaction between actin and myosin.

4. **Conclude the Answer**:
Since the question asks for the main proteins of striated muscles, the answer includes actin, myosin, tropomyosin, and troponin. Therefore, the correct answer is option 4: All of these.