A classmate is working with a source that is labelled 18 V. The classmate refers to
the source as a cell. Why might you think
that the term cell is incorrect? How is the
source most likely related to a cell?​

The term cell is incorrect because, the average voltage of a cell is 3.40 V and as already mentioned in question, the volt of source is 18 V, so cell couldn't be the appropriate word, actually the source is battery.

Now, the source is most likely related to cell because a battery which is the source here, is made up of a "group of cell".

c because the news are a source of information of things that happen on the daily and shows evidence about that particular topic

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me