Which can be categorized as a use of plasma in technology?

taking pictures of solar flares

observing the aurora borealis

making fluorescent lights for houses

making telescopes to observe distant stars

As making fluorescent lights for house uses the technology of using plasma for lightning purposes in houses.

Whereas the other options are not relevant to use the plasma technology, as taking pictures does not implies the use of plasma technology.

Observing the aurora borealis is not a technology even though auroras are observed because of plasma.

Making telescopes to observe distance stars does not employs use of plasma technology.

And the fluorescent lights which are used at houses work on ionizing mechanism of mercury vapor which is stored in a glass tube. Which causes the electrons present in the gas to emit photons at the range of UV frequencies.

Then this UV light is found to be converted into standard visible light by using a phosphor coating done inside of the tube.

elements make up everything, and they combine to make compounds.

the answer is c