(Calc 1) Need help understanding this graph pls I tried to do it but it was wrong

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

With this question! what is process of elimination? ? p.s. my brothers acc got banned so add his new one @ yamauchiyamyam17

There are 18 female students and 16 male students in a class. which of the following expresses the ratio of female students to male students in simplest form? а) 10 b) 9 to 8 c) 8: 9 d)18/16