Answer: Option (C) is the correct answer.
Step-by-step explanation:
Heat capacity is defined as the heat amount required to raise one degree temperature of a system.
Heat capacity of water is 4.184 J and heat capacity of sand is 0.290 J. So, less is the value of heat capacity of a substance more is the amount of heat absorbed by it.
Whereas substances which are able to conduct heat and electricity efficiently are known as conductors. The substances which are not able to efficiently conduct heat and electricity are known as insulators.
Therefore, water is a better insulator as compared to sand as it does not heat readily.
Thus, Josh concludes that water is the better insulator, is true.