Which surface was warmer during the month of October? The pond or the sidewalk?

The pond was warmer during the month of October.

Explanation:

Water has a high specific heat capacity, therefore more heat is required to change its temperature. This is why aquatic life is able to stay alive even when temperatures drop drastically. The sidewalk however, will more than likely adapt to the temperature change quickly as concrete does not have a very high specific heat capacity.

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.