The first question (A) is incomplete as the sentence is cut off. I will solve question D.

The perimeter $P$ of a square with side length $s$ is given by:

$$P = 4s$$

$$P = 10 \text{ cm}$$

The perimeter of the square is $\boxed{\text{10 cm}}$.

The perimeter $P$ of a parallelogram with adjacent side lengths $a$ and $b$ is given by:

$$P = 2(a+b)$$

$$P = 2(6 \text{ cm})$$ $$P = 12 \text{ cm}$$

The perimeter of the parallelogram is $\boxed{\text{12 cm}}$.