Sheet M is rolled to form an open cylinder by bringing the shorter edge of the sheet together
So the longer side becomes the circumference of the base of the cylinder and shorter side becomes the height.
$\therefore 2\times\pi\times r = 6 \\\implies r = \frac{3}{\pi}$
$\text{Volume of cyclinder} = \pi\times r^2 \times h = \pi\times {(\frac{3}{\pi})}^2\times 1 = \frac{9}{\pi}$
Sheet N is cut into equal square patches and assembled to form the largest possible closed cube
So the entire area of the sheet is converted into surface area of the cube, i.e.
$6\times a^2 = 6 \times 1\\\implies a^2 = 1\\\implies a = 1$
$\text{Volume of cube} = a^3 = (1)^3 = 1$
$\frac{\text{Volume of cylinder}}{\text{Volume of cube}} = \frac{\frac{9}{\pi}}{1} = \frac{9}{\pi}$
Option C