Answer: The correct option is (D) 18°.
Step-by-step explanation: The given circle in the figure shows a family's water usage for a year.
We are given to find the central angle for gardening.
From the figure, we note that gardening covers 5% of the whole circle.
The complete central angle for a circle is 360°.
So, the central angle for gardening will be 5% of 360°.
Therefore, the central angle for gardening is given by
\(C_g=5\%\times 360^\circ=\dfrac{5}{100}\times 360^\circ=18^\circ.\)
Thus, the correct option is (D) 18°.
