Given data is that circles are identical. According to this diameters are identical too.
Diameter of the first circle is 4x and for the second 2x+3.
We can make equality 4x = 2x+3 => 2x=3 => x=3/2
Circumference of each circle is C= 2r pi = 2*(3/2) pi = 3 pi
The correct is fifth answer.
Good luck!