To determine the floor area of a square room, we follow these steps:
1. Identify the side length of the square room. In this case, the side length is given as 12 feet.
2. Use the formula for the area of a square, which is side length squared (side length × side length).
3. Calculate the area by squaring the side length:
[tex]\[
\text{Area} = 12 \, \text{feet} \times 12 \, \text{feet} = 144 \, \text{square feet}
\][/tex]
Thus, the floor area of the square room is [tex]\(\boxed{144 \, \text{sq. ft.}}\)[/tex].
Therefore, the correct answer is:
D
144 sq. ft.
