To find the area of a square, you use the formula:
\[ \text{Area} = \text{side} \times \text{side} \]
In this case, the side of the square is 5 cm. Therefore, the area is:
\[ \text{Area} = 5 , \text{cm} \times 5 , \text{cm} = 25 , \text{cm}^2 \]
The best answer is D. 25cm².