Can someone please explain to me this image?

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

Which function families have maximums and minimums? 1.)linear absolute value functions and exponential functions 2.) linear absolute value functions and quadratic functions 3.) linear absolute value functions and linear functions 4.) linear absolute value functions and constant functions

I'm confused on this could anyone me and show me what i need to do to solve it.