Identify the correct statement from the following .

Options

A. Major proteins are synthesized in SER.
B. RER also involved in synthesis of steroidal hormone in animal cells.
C. RER commonly observed in cells which actively involved in secretion.
D. All the above statements are correct.

Answer

To identify the correct statement from the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Evaluate the First Statement**:
- **Statement**: "Most proteins are synthesized in smooth endoplasmic reticulum."
- **Analysis**: This statement is incorrect. The majority of protein synthesis occurs in the rough endoplasmic reticulum (RER), not the smooth endoplasmic reticulum (SER). The RER is studded with ribosomes, which are the sites of protein synthesis.

2. **Evaluate the Second Statement**:
- **Statement**: "Rough endoplasmic reticulum is involved in the synthesis of steroidal hormones in animal cells."
- **Analysis**: This statement is also incorrect. The smooth endoplasmic reticulum (SER) is responsible for the synthesis of steroid hormones, while the rough endoplasmic reticulum is primarily involved in the synthesis of proteins.

3. **Evaluate the Third Statement**:
- **Statement**: "Rough endoplasmic reticulum commonly observed in the cells which are actively involved in secretion."
- **Analysis**: This statement is correct. The rough endoplasmic reticulum is abundant in cells that are actively synthesizing and secreting proteins, such as pancreatic cells that produce digestive enzymes.

4. **Evaluate the Fourth Statement**:
- **Statement**: "All the above statements are correct."
- **Analysis**: This statement is incorrect because the first two statements have been identified as wrong.

### Conclusion:
- The only correct statement among the given options is the third statement: "Rough endoplasmic reticulum commonly observed in the cells which are actively involved in secretion."

### Final Answer:
The correct statement is: **"Rough endoplasmic reticulum commonly observed in the cells which are actively involved in secretion."**

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