Answer:
c. y = -x + 4
Explanation:
Looking at the graph, the trend is decreasing as you move to the right, so you know that the slope has to be negative. Therefore (a) and (d) cannot be the answer since they both have positive slope.
You're only choice left is (b) and (c). (b) can't be the asnwer because averaging out the value at x=0 will give you a value greater than 3, therefore your y-intercept must be some number greater than 3. The only answer choice left is (c).