The correct option is A organogens
The elements hydrogen, oxygen, carbon and nitrogen are not halogens as halogens include - chlorine, bromine, fluorine, iodine. Alkali metals are elements which belongs to group 1 and includes – hydrogen, lithium, potassium, sodium, rubidium, etc. So only hydrogen belongs to alkali metals. Isotopes are two or more forms of the same element that contains equal numbers of protons but different numbers of neutrons in the nuclei. Whereas organogens are substances derived from organic compounds such as plants and animals. Therefore all these elements are organogens.