The correct answer is option 'C', which states that the power development programmes that are possible in Tamil Nadu are largely based on nuclear power plants.

Nuclear power plants are one of the major sources of electricity generation worldwide, and they play a significant role in meeting the growing energy demands. Tamil Nadu, being a state in India, also relies on nuclear power plants for its power development programmes.

There are several reasons why nuclear power plants are a viable option for power development in Tamil Nadu:

1. **Energy Efficiency**: Nuclear power plants are highly efficient in converting nuclear energy into electricity. The process involves nuclear fission, where the nucleus of an atom is split, releasing a large amount of energy. This energy is then converted into electricity using turbines and generators. The efficiency of nuclear power plants is much higher compared to other conventional power plants, such as steam or diesel power plants.

2. **Reliability**: Nuclear power plants provide a reliable source of electricity. Unlike renewable energy sources like solar or wind, which are dependent on weather conditions, nuclear power plants can operate consistently throughout the year, providing a stable supply of electricity. This is particularly important in Tamil Nadu, where the demand for electricity is high and needs to be met consistently.

3. **Scalability**: Nuclear power plants have the advantage of scalability. They can be designed to meet the specific energy requirements of a region or state. Tamil Nadu, being a highly industrialized state with a growing population, requires a significant amount of electricity. Nuclear power plants can be designed and expanded accordingly to meet the increasing demand for electricity in the state.

4. **Environmentally Friendly**: Nuclear power plants do not emit greenhouse gases like coal-fired power plants, which contribute to climate change. They provide a clean source of energy and help reduce the carbon footprint. This is in line with global efforts to transition towards cleaner and more sustainable energy sources.

5. **Safety Measures**: Nuclear power plants are designed with strict safety measures to prevent accidents and protect the environment and public health. The plants are equipped with multiple layers of safety systems, including containment structures and emergency shutdown mechanisms. The operators of nuclear power plants undergo extensive training to ensure safe and efficient operation.

In conclusion, the power development programmes in Tamil Nadu are largely based on nuclear power plants due to their energy efficiency, reliability, scalability, environmental benefits, and safety measures. These factors make nuclear power plants a suitable and sustainable option for meeting the increasing electricity demand in the state.