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
In 18 minutes, the maximum gallons of water is given by
Hence, Option 'D' is correct.