PQRS is a square whose side is 16 cm. What is the value of the side (in cm) of the largest regular octagon that can be cut from the given square?

A

$$8 - 4\surd2$$

B

$$16 + 8\surd2$$

C

$$16\surd2 - \surd16$$

D

$$16 - 8\surd2$$