Answer: The third option.
Explanation:
You can write the following equation of the line of the exercise:

Where:
y=s
x=r
m is the slope.
b is the intersection of the line with the y-axis (Identified as "s").
The slope can be calculated as following:

As you can see in the graph, when r=0, s=10, therefore, the intersection of the line with the y-axis (Identified as "s") is:
b=10
Therefore, the equation is:

Then, you must look for a graph that has a slope 1 and that the line intersects the y-axis (Identified as "s") at 10 (r=0, s=10)
This would be the third graph.