Which graph below represents a function?
Image Description: Four graphs on coordinate planes.
Graph (1): Five points plotted at (1,1), (2,2), (3,2), (4,4), and (5,4).
Graph (3): Six points plotted at (1,1), (2,2), (2,3), (2,4), (2,5), and (5,4).
Graph (2): A step function with horizontal segments. An open circle at (1,1) with a horizontal line to a closed circle at (3,1). An open circle at (3,3) with a horizontal line to a closed circle at (4,3). A closed circle at (4,5) with a horizontal line to a closed circle at (5,5).
Graph (4): A step function with vertical segments. A closed circle at (1,1) with a vertical line to a closed circle at (1,3). A horizontal line to a closed circle at (3,3), then a vertical line up to a closed circle at (3,4). A horizontal line to an open circle at (5,4), then a vertical line up to an open circle at (5,5).
(1) Graph 1
(2) Graph 2
(3) Graph 3
(4) Graph 4