The answer is letter d. it has only 2 electrons in its first shell and 4 in the second shell. Basing from the electronic configuration of the carbon atom, the "s" orbital of carbon atom is completely filled leaving now the "p" orbitals partially filled. Thus in this case, carbon atom has four (4) valence electrons.
I think it's water because it says abiotic feature and abiotic means non-living, although the water has living animals and bacteria in it, the water itself isn't living.
