The right option is; d. sulfur
Thermoacidophile archaebacteria are a type of archaea that thrive in extremely hot and strong acidic (with low PH) environments. Thermoacidophile archaebacteria can be found in harsh environments such as in geothermal area, in the deep ocean vents and hot springs. Most of the Thermoacidophile archaebacteria are chemotrophs (converts chemicals to food). They use sulfur as their energy source. They absorb the sulfur gas that is being released in their environment and reduce it to hydrogen sulphide, fixing it into an energy source.