Chorion is:-
Trophoblast with mesoderm
Trophoblast with splanchnopleuric mesoderm
Trophoblast with somatopleuric mesoderm
None of above
Somatotropic mesoderm along with cytotrophoblast is called chorion. Somatopleuric layer lines the cyto-trophoblast and amnion; and splanchno pleuric layer covers the primary yolk sac. The extra embryonic coelom divides the extra embryonic mesoderm into somatopleuric and splanchnopleuric layers.
General Embryology 1