The best estimate for this correlation would be B) 0.9.
We can see that the number is constantly going up, which would throw out the D answer.
We can also see that for every time the x goes up 1, the y goes up a little less than one. We can see that in the ordered pairs that exist on the graph such as (3, 2), (8, 6) and (2.1, 1.9).
Since the y values are just lower than the x, the correlation would be just under one. Therefore, 0.9 is an accurate estimation.