Answer: The correct option first, i.e., f(x)=x-3.
Step-by-step explanation:
From the given graph it is noticed that the y intercept of the line is (0,-3) and the x intercept of the line is (3,0).
The equation of line which passing through two points
and
.

The equation of line passing through (3,0) and (0,-3),




Therefore the correct option is first, i.e., f(x)=x-3.