In which of the following heat loss is primarily not due to convection?

Options

A. boiling of water
B. land and sea breeze
C. heating of glass surface of a bulb due to current in filament
D. circulation of air around blast furnace.

Explanation

To solve the problem of identifying which heat loss is primarily not due to convection, we need to analyze the different methods of heat transfer: conduction, convection, and radiation.

### Step-by-Step Solution:

1. **Understand Heat Transfer Methods**:
- Heat can be transferred in three ways: conduction, convection, and radiation.
- **Convection** occurs in fluids (liquids and gases) where heat is transferred through the movement of the fluid itself.
- **Conduction** is the transfer of heat through a solid material without the movement of the material itself.
- **Radiation** is the transfer of heat in the form of electromagnetic waves and does not require a medium.

2. **Identify the Options**:
- The question asks us to determine which option involves heat loss that is primarily not due to convection.
- We need to evaluate each option to see if it involves fluid motion or not.

3. **Evaluate Each Option**:
- **Option A**: Heating of water (boiling) - This involves convection as the water moves and circulates.
- **Option B**: Air circulation around a blast furnace - This also involves convection as the air moves due to temperature differences.
- **Option C**: Heating of a gas surface of a bulb due to a current in a filament - This does not involve fluid motion; instead, it primarily involves radiation as the heat is transferred from the filament to the surface without the need for a fluid medium.
- **Option D**: Land and sea breeze - This is a classic example of convection due to the movement of air.

4. **Conclusion**:
- The option that involves heat loss primarily not due to convection is **Option C**: Heating of gas surface of a bulb due to a current in a filament.

### Final Answer:
**Option C**: Heating of gas surface of a bulb due to a current in a filament.

---