To get the hexagon on the righ from the figure on the left we have to multiply the length of each side by a scale factor "x", as you can see, for the bottom side of the figures we go from 10 to 14, then we can formulate the following expression:
10x = 14
From this equation, we can solve for x to get:
x = 14/10
x = 7/5
Then, the scale factor equals 7/5, the correct answer is the last one