Answer:
visually locate the steepest line, or the one "on top" to the right of where they cross
Explanation:
The rate of increase of a graph is the ratio of "rise" to "run" (the slope). The graph with the fastest rate of increase will have more "rise" (upward change) for the same "run" (horizontal change to the right).
In general, you don't need to measure or calculate the slope to tell which graph has the fastest rate of increase. It will be the line that is the steepest going toward the upper right.
If the lines cross at some point, the steepest slope (fastest rate of increase) is associated with the line that has the highest y-coordinate values (is "on top") to the right of the point where the lines cross.