Besides water and light which is more essential as a raw material for food formation

Options

A. `CO_(2)`
B. `NAD`
C. `O_(2)`
D. Mineral salts.

Answer

To answer the question "Besides water and light, which is more essential as a raw material for food formation?" we will analyze the options provided and determine the correct answer step by step.

### Step 1: Identify the process of photosynthesis
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose (a carbohydrate). This process primarily requires three raw materials: water, light, and carbon dioxide.

**Hint:** Remember that photosynthesis occurs in two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle).

### Step 2: Analyze the options
The options given are:
1. Carbon dioxide
2. NAD (Nicotinamide adenine dinucleotide)
3. Oxygen
4. Mineral salts

**Hint:** Consider the role of each option in the process of photosynthesis.

### Step 3: Evaluate each option
- **Carbon dioxide:** This is a crucial raw material in photosynthesis. It is absorbed from the atmosphere and used in the Calvin cycle to produce glucose.

- **NAD:** While NAD is important as an electron carrier in cellular respiration and photosynthesis, it is not a raw material for food formation.

- **Oxygen:** Oxygen is a byproduct of photosynthesis, not a raw material. It is released into the atmosphere during the process.

- **Mineral salts:** These are important for plant growth and health but are not directly involved in the food formation process during photosynthesis.

**Hint:** Focus on which of these substances is directly used to create glucose during photosynthesis.

### Step 4: Conclusion
After evaluating the options, it is clear that carbon dioxide is the most essential raw material for food formation, alongside water and light. It is utilized in the synthesis of carbohydrates during photosynthesis.

**Final Answer:** The correct option is **carbon dioxide**.