Phosphorus is the major constituients of
(a) Biological membrane
(b) Nucleic acid
(c) Cellular energy transfer system
(d) proteins

Options

A. a,b and c
B. b,c and d
C. a,b, and d
D. a,b,c and d

Explanation

To solve the question regarding which of the following options phosphorus is a major constituent of, we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Phosphorus**:
- Phosphorus is an essential element in biological systems. It plays a crucial role in various biological molecules.

2. **Option A - Biological Membrane**:
- Biological membranes, such as the phospholipid bilayer, contain phospholipids which have phosphate groups. Therefore, phosphorus is indeed a major constituent of biological membranes.

3. **Option B - Nucleic Acid**:
- Nucleic acids (DNA and RNA) contain phosphate groups in their backbone structure. This makes phosphorus a critical component of nucleic acids.

4. **Option C - Cellular Energy Transfer System**:
- ATP (adenosine triphosphate), the primary energy carrier in cells, contains three phosphate groups. Thus, phosphorus is a major constituent of the cellular energy transfer system.

5. **Option D - Proteins**:
- Proteins are made up of amino acids, which do not contain phosphorus as a major component. Therefore, phosphorus is not a significant constituent of proteins.

6. **Conclusion**:
- Based on the analysis, phosphorus is a major constituent of options A (Biological Membrane), B (Nucleic Acid), and C (Cellular Energy Transfer System). The correct answer is therefore A, B, and C.

### Final Answer:
Phosphorus is the major constituent of:
- (a) Biological membrane
- (b) Nucleic acid
- (c) Cellular energy transfer system