Step 1: Define renewable vs non-renewable.
Renewable resources replenish naturally on a human timescale (solar, wind, hydro, biomass). Non-renewables (coal, oil, uranium, thorium) are finite and deplete with use.
Step 2: Apply to options.
Solar energy is inexhaustible at the human scale; Uranium and Thorium are nuclear fuels extracted from ores—non-renewable.
Step 3: Conclude.
\[
\boxed{\text{Solar energy (Option A).}}
\]