Galactic recycling is a natural phenomenon in which the stars expel some gas into the space so that it would mix with the interstellar medium. As a result, this would produce new younger stars. So, basically, the concept done here is the mass and energy conservation. In order to create new species, the energy must come from another source.
C) It contains the same number of electrons and protons.
I think it's Sodium Sulfide, because Na2S contains one Sodium and two Sulfur. Plus Sulfide<span> is used to describe any of three types of chemical compounds that contain sulfur.</span>
