In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
vertical line test = ?
horizontal line test = ?
Step 02:
vertical line test ===> function
any vertical line intersect the graph at only one point
horizontal line test ===> invertible
any horizontal line intersect the graph at only one point
graph:
horizontal line test = red
vertical line test = brown
That is the full solution.