A company wants to start a nuclear power plant as a way to produce clean energy. They want to use the same reaction that's used in thermonuclear weapons. Which of the following explains why this is not possible?

This is not possible due to the international policies on armaments.

Explanation:

The international community through unesco regulates the development of weapons of mars destruction hence cannot allow the country to just use chemicals or even materail used for development of nuclear weapons to develop nuclear energy.

The other reason is that, the intentions ot the project may not be known since it can as well be used for thed evelopment of weapons of mass destruction, with a prop of nuclear energy.

It is not possible to generate clean energy from nuclear fusion reaction (one that is used in thermonuclear weapons) because the energy in nuclear fusion can't be generated in a controlled manner.

Explanation:

Unlike nuclear fission in which atoms of radioactive isotopes are split to obtain enormous amount of energy, in nuclear fusion, the nuclei of two different atoms are combined to obtain energy. In an Earth-based setting, it is nearly impossible to keep feeding a nuclear fusion reaction with the required amount of energy to produce clean energy in return. The United States of America carried out fusion reactions in an uncontrolled way (by exploding hydrogen bombs) to produce thermonuclear weapons. A nuclear fusion reaction generates several megatons of energy in a fraction of second. Thus, the energy in nuclear fusion cannot be generated in a controlled manner.