Answer: first, second, and third images.
Explanation:
to determine if something is a function, the domain must not have more than one answer in the range. My class calls it the y axis test, if you were to graph it, you cannot draw a line straight down that will go through two points. it's easy to understand with images like these, because all you need to know is that arrows cannot go from one number on the left to multiple on the right. Vice versa is a function, because it passes the y axis test.