Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?

1. The origin of life on Earth is believed to have occurred through abiogenesis, the process by which life arises from non-living matter. 2. The building blocks of life as we know it – including amino acids, nucleic acids (DNA/RNA), lipids, and carbohydrates – are organic molecules. 3. Organic molecules are fundamentally based on carbon. 4. The most abundant elements in organic molecules and living organisms are Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). Phosphorus (P) and Sulfur (S) are also crucial. 5. The early Earth's atmosphere is thought to have been reducing, containing compounds like methane (CH4), ammonia (NH3), water vapor (H2O), and hydrogen (H2). These molecules contain the key elements Carbon, Hydrogen, and Nitrogen. 6. Option (A) includes Sodium, which is important for life but not as fundamental as C, H, N, O for the basic structure of organic molecules. 7. Option (B) (Carbon, Hydrogen, Nitrogen) lists three of the four most essential elements forming the backbone of life's molecules. Early atmospheric conditions and experiments like Miller-Urey suggest these were key. 8. Option (C) includes Calcium and Phosphorus. While essential (especially P for DNA/RNA/ATP), they are not typically considered the primary structural elements in the same way as C, H, N, O. 9. Option (D) includes Potassium, which like Sodium, is vital for cellular function but not a primary structural element of basic organic molecules. 10. Therefore, the set Carbon, Hydrogen, Nitrogen represents the elements most fundamentally responsible for the origin of life's building blocks.