Answer: D. y = x+7
We can rule out choices A and B since they have a negative slope.
We can rule out choice C because the y intercept is nowhere near 42.
The y intercept isn't clear, but if we draw a line so that it is as close as possible to all the points, then it hits around the 5 to 10 range, so 7 is a fairly good estimate. Choice D is the only answer choice left, so its the best estimate.
See the diagram below.