The four elements called "big-four" which make up 95% of all elements found in a living system are

Options

A. C, H, O, N
B. C, H, O , P
C. C, H, O, S
D. C, N, O , P

Answer

To answer the question about the four elements known as the "big-four" that make up 95% of all elements found in living systems, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify the four primary elements that constitute a significant portion of living organisms.

2. **Identifying the Elements**: The question refers to the "big-four" elements that are essential for life. These elements are:
- **Carbon (C)**: Fundamental for the structure of biomolecules.
- **Hydrogen (H)**: A key component of water and organic compounds.
- **Oxygen (O)**: Essential for respiration and a major part of water and organic molecules.
- **Nitrogen (N)**: A critical element in amino acids and nucleic acids.

3. **Confirming Their Importance**: These four elements together account for approximately 95% of the mass of living organisms. They are the building blocks of various biomolecules such as carbohydrates, proteins, lipids, and nucleic acids.

4. **Conclusion**: Therefore, the four elements known as the "big-four" that make up 95% of all elements found in living systems are Carbon, Hydrogen, Oxygen, and Nitrogen.

### Final Answer:
The four elements called the "big-four" which make up 95% of all elements found in a living system are **Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N)**.

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