What is the primary reason fusion is not used in power plants? fusion causes too much air pollution. fission generates more energy than fusion. the cost of using fusion in a practical way is too high. current technology is unable to control the reaction?

the cost of using fusion in a practical way is too high.

Explanation:

When two smaller unstable nuclei combine to make a stable nuclei then this process of stability of nuclei is known as nuclear fusion.

In this process of nuclear fusion the energy is released due to stability but in this process the initial energy is required to start the reaction.

This process of starting the reaction is relatively of high cost as compare to nuclear fission reaction.

So here correct answer will be

the cost of using fusion in a practical way is too high.

d is the correct answer

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures