In a muscle fibre :

Options

A. sacrolemma is connective tissue holding the myofibrils together
B. T system contains calcium storage sacs
C. both filaments have cross-bridges
D. all of the above

Explanation

To solve the question regarding muscle fibers, we will analyze each option provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding Sarcolemma**:
- The first option states that the sarcolemma is a connective tissue holding the myofibrils together.
- **Correction**: Sarcolemma is actually a membrane that surrounds the muscle fiber, not a connective tissue. Therefore, this option is incorrect.

2. **Analyzing the T-System**:
- The second option claims that the T-system contains calcium storage sacs.
- **Explanation**: The T-system, also known as T-tubules, is closely associated with the sarcoplasmic reticulum, which is responsible for storing calcium ions. The terminal cisternae of the sarcoplasmic reticulum are indeed calcium storage sites. Thus, this option is correct.

3. **Examining Cross Linkage of Filaments**:
- The third option states that both filaments (actin and myosin) have cross-linkage.
- **Clarification**: Cross-linkage between actin and myosin filaments occurs specifically during muscle contraction, not at all times. Therefore, this statement is misleading and incorrect.

4. **Evaluating the Final Option**:
- The fourth option suggests that all of the above statements are correct.
- **Conclusion**: Since we have identified that only the second option is correct, this option is also incorrect.

### Final Answer:
Based on the analysis, the correct answer is **Option 2**: The T-system contains calcium storage sacs.

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