Arock rolls from the top of the hill to the bottom. the total energy of the rock at top isn't the same as the sum of its energy at the bottom which statement best explains this situation

Some of the details are missing but we can construct our own statement which would explain the situation.
A rock starts on top of the hill and all of its energy is potential energy. When it starts rolling down the hill this potential energy is being used.
Some of the potential energy is transferred to kinetical energy (energy of motion) and some of it is used to work against friction. Force of friction creates heat and this heat is dissipated into the environment so essentially it is lost.
The statement would be something like this:
As rock rolls down the hill, it loses some of its initial energy due to friction.

I'll do it rn and then answer

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling