Solar heating is the system composed of a fluid system to move the heat from the collector to its point of usage and a reservoir to stock the heat
Step-by-step explanation:
The options given here like coal burning uses solid material as the source to heat and to generate energy. Similarly, nuclear power also requires solid particles like atoms or neutrons to strike the moderators forming energy.
In both of these cases, fluid system is present but it is used completely as coolant and to maintain the temperature. Thus, the remaining system that is solar heating has been done for water tanks where the fluid as water is used to move the heat from its collector to its point of usage. Even in solar system it is used as reservoir to stock the heat.