African, Asian and european human beings have some permanent variations in some of the traits like skin colour, hair styles, shape of nose, thickness of lips etc. Africans and europeans show extremes in these traits whereas the Asians are of intermediate types, for example, the skin colour. Africans are black, europeans are white and Asians have brown skin.
On the basis of above traits the Asians, African and europeans are :-
(1) Three ecotypes of one species
(2) Three biotypes of one species
(3) Three ecads of some species
(4) One sibling species
Variant 1 is correct. Ecotype is a group of organisms within a species that is adapted to particular environmental conditions and therefore exhibits behavioural, structural, or physiological differences from other members of the species. Races of humans appeared because of adaptation to different conditions. For example, Africans are black because they produce melanin, which protects them from the sun.