Answer:
b. f(x) = -2x +2
Explanation:
The graph has a negative slope (m < 0) and a positive y-intercept (b > 0). The only equation with those characteristics is ...
f(x) = -2x +2
_____
Additional comment
The line on the graph appears to fall by 2 grid squares for each 3 to the right. That means it has a slope of ...
m = rise/run = -2/3
None of the offered equations have that slope. We have to assume the graph is "not to scale". Hence we can only comment on the signs of slope and intercept, and not their values.
You may want to discuss this question with your teacher.