Which relation is a function? a coordinate grid with graph of a curve that increases through the third quadrant through the origin and exits the first quadrant a coordinate grid containing a u shape with arrows on both ends that opens to the right. the bottom portion of the u passes through the origin. a coordinate grid with the graph of a circle centered at the origin and passing through the point begin ordered pair 2 comma 1 end ordered pair. coordinate grid with graph of a vertical line at x equals 3.ma 3 end ordered pair and begin ordered pair 3 comma 4 end ordered pair.