Answer:
Water, high specific heat capacity
Step-by-step explanation:
The temperature fluctuations are relatively small in Jameson city because takes water longer to heat up and cool down due to its high specific heat capacity because water has high heat capacity that is it absorb alot of heat before it start to get hot. takes more energy to increase the temperature of water compared to other substances which help to regulate extremes in the environment.
Water surrounding cities take longer to heat up and longer to cool down so cities that are near the oceans will tend to have less change and less extreme temperatures compared to inland cities.