Final answer:
The change in the amount of water in the pool each minute is 6 gallons per minute.
Step-by-step explanation:
To find the change in the amount of water in the pool each minute, we divide the total amount of water pumped by the amount of time it took. In this case, Keiko pumped 36 gallons of water over a period of 6 minutes. So, the change in the amount of water in the pool each minute is 36 divided by 6, which is 6 gallons per minute. Therefore, the correct option is Option 1: 6 gallons per minute.