To solve the question regarding the correct set of macronutrients, we will follow these steps:
### Step 1: Understand Macronutrients and Micronutrients
- Macronutrients are nutrients required by plants in larger quantities (more than 10 millimoles per kg of dry matter).
- Micronutrients are required in smaller quantities (less than 10 millimoles per kg of dry matter).
### Step 2: Identify Common Macronutrients
- Common macronutrients for plants include:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- Phosphorus (P)
- Potassium (K)
- Calcium (Ca)
- Magnesium (Mg)
- Sulfur (S)
### Step 3: Analyze the Given Options
- The options provided are:
1. Potassium, Boron
2. Potassium, Hydrogen, Magnesium
3. Nitrogen, Carbon, Zinc
4. Hydrogen, Nitrogen, Carbon, Hydrogen, Magnesium, Nitrogen
### Step 4: Evaluate Each Option
1. **Potassium, Boron**: Potassium is a macronutrient, but Boron is a micronutrient. **(Incorrect)**
2. **Potassium, Hydrogen, Magnesium**: All three (Potassium, Hydrogen, and Magnesium) are macronutrients. **(Correct)**
3. **Nitrogen, Carbon, Zinc**: Nitrogen and Carbon are macronutrients, but Zinc is a micronutrient. **(Incorrect)**
4. **Hydrogen, Nitrogen, Carbon, Hydrogen, Magnesium, Nitrogen**: Hydrogen, Nitrogen, Carbon, and Magnesium are all macronutrients. **(Correct)**
### Step 5: Conclusion
- The correct sets of macronutrients are found in options 2 and 4. However, since the question asks for a "set," we can conclude that option 2 is the most straightforward and correct set of macronutrients.
### Final Answer
- The correct set of macronutrients is **Potassium, Hydrogen, Magnesium**.
