Which four elements make up the bulk of living cells?

• A. Carbon, calcium, sodium, and oxygen
• B. Calcium, phosphorus, potassium, and sulfur
• C. Carbon, hydrogen, oxygen, and nitrogen
• D. Sodium, chlorine, magnesium, and iron

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the context of the question. Living cells are primarily composed of elements that are essential for forming biomolecules such as carbohydrates, proteins, lipids, and nucleic acids.
2. Step 2: Recall the major biomolecules in living organisms. These include carbohydrates, proteins, lipids, and nucleic acids, which are primarily composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).
3. Step 3: Eliminate incorrect options by considering the roles of the elements listed. For example, calcium, sodium, and phosphorus are important for specific functions like signaling and bone structure but do not make up the bulk of living cells.
4. Step 4: Focus on the correct elements. Carbon, hydrogen, oxygen, and nitrogen are the primary elements that form the backbone of organic molecules and are found in the highest abundance in living cells.
5. Step 5: Confirm the correct answer by matching it to the explanation above. The correct answer is: Carbon, hydrogen, oxygen, and nitrogen.