Yes, you are correct, it is A!
Recall the pencil line test, which is where you go across the x axis (the graph horizontally) and see if the pencil touches any two points at the same time. If it does, then the graph is not a function.
Point being: since question a has a bunch of y values on top of one x value, the pencil would inevitably touch multiple at the same time, hence why it is easy to tell that it is not a function! Hope this helps :)
$41.04 you multiply how long and how wide it is together. after that that the answer is 2,070 then divide it by 50 and you get $41.04.
i hope that helps!!
If you were to plan a party, you could use a linear equation. for example, the room you are renting is $500. The price for food per person is $10