For this case we have a function of the form:

 Where,
 m: slope of the line
 b: cutting point with the y axis.
 The line cuts to the y-axis at the point:

 Therefore, the value of b is given by:
 
 We now look for the slope of the line.
 For this, we use the following equation:
 
 Substituting values we have:
 
 Rewriting:
 
 Then, the equation of the line is:
 
 Answer:
 the rule that matches the function shown in the graph is:
 