Answer the following question given this paragraph: 

32.5 Fusion While basking in the warmth of the summer sun, a student reads of the latest breakthrough in achieving sustained thermonuclear power and vaguely recalls hearing about the cold fusion controversy. The three are connected. The Sun’s energy is produced by nuclear fusion (see Figure 32.15). Thermonuclear power is the name given to the use of controlled nuclear fusion as an energy source. While research in the area of thermonuclear power is progressing, high temperatures and containment difficulties remain. The cold fusion controversy centered around unsubstantiated claims of practical fusion power at room temperatures.


Q: What is the name given to the use of controlled nuclear fusion as an energy source?

 Choices:

- generator power

- half-life

- fossil fuel

- thermonuclear power

A:
thermonuclear power
