Answer:
Scatterplot 2
Explanation:
SP1: All a straight line with equation of y=3 except for 1 point.
SP2: All points are on the line of y=2x-1
SP3: The trend line is y=2x-1, however, a lot of points aren't on it
SP4: Same as SP3, but there is an additional outlier at x=1.8
SP2 looks to be the strongest correlation based on these descriptions.