The scatterplot that shows a linear association is the first one:
x values: 5, 8, 2, 4, 6, 12, 10, 1, 3, 7
y values: 800, 700, 350, 450, 500, 1000, 900, 250, 400, 750
The relationship between the x and y values in this scatterplot appears to be linear.