Calculate the area of the shaded regions in the given grids.

The grid has 4 rows and 4 columns.

Area $= 4 \times 4 = 16 \text{ cm}^2$.

The correct option is (d).
The area is $\boxed{\text{16 cm}^2}$.

2.

The grid has 4 rows and 8 columns.

Area $= 4 \times 8 = 32 \text{ cm}^2$.

The correct option is (a).
The area is $\boxed{\text{32 cm}^2}$.

3.

The grid has 3 rows and 3 columns.

Area $= 3 \times 3 = 9 \text{ cm}^2$.

The correct option is (b).
The area is $\boxed{\text{9 cm}^2}$.

4.

The grid has 4 rows and 4 columns.

Area $= 4 \times 4 = 16 \text{ cm}^2$.

The correct option is (d).
The area is $\boxed{\text{16 cm}^2}$.

5.

The grid has 5 rows and 5 columns.

Area $= 5 \times 5 = 25 \text{ cm}^2$.

The correct option is (b).
The area is $\boxed{\text{25 cm}^2}$.