Answer: Option 'D' is correct.
Step-by-step explanation:
Since we have given that
In a 4 minute, the shower uses an average of 20-40 gallons of water,
If we consider the maximum gallons of water,
In 4 minutes, the maximum gallons of water = 40
In 1 minute, the maximum gallons of water is given by
![\frac{40}{4}=10](https://tex.z-dn.net/?f=%5Cfrac%7B40%7D%7B4%7D%3D10)
In 18 minutes, the maximum gallons of water is given by
![18\times 10=180\ gallons](https://tex.z-dn.net/?f=18%5Ctimes%2010%3D180%5C%20gallons)
Hence, Option 'D' is correct.