Answer:
Chlorine (Cl). Option C is correct
Explanations:
For an elements to be stable, it must attain its octet configuration that is the total number of electron in its outermost shell is must be 8 electrons.
For sulphur (atomic number of 16) with an electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^4. This shows that sulphur needs 2 electrons to complete its shell making the first option incorrect.
For hydrogen (atomic number of 1) will need one electron to attain duplet rule making the option B is incorrect.
For chlorine element (atomic number of 17), with electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^5. This shows that chlorine will need 1 more electron to make it stable