To find the area of a rectangle, you use the formula:
\[ \text{Area} = \text{length} \times \text{width} \]
In this case, the length (l) is 9 ft and the width (w) is 5 ft.
Calculating the area:
\[ \text{Area} = 9 , \text{ft} \times 5 , \text{ft} = 45 , \text{ft}^2 \]
The best answer is C. 45ft².