Correct Answer - B
(d) Amnion is an extra embryonic membrane that surrounds embryo in reptitles, birds and mammals. It provides a kind of private aquarium to the embryo and protects it from mechanical shock and desicaction.
Chorion (serosa) is the outermost extra embryonic membrane is rptiles, birds and mammals.it surrounds the whole enbryonic system of embryo. Yolk sac contains yolk in reptiles and birds. in mammals yolk sac is also known umbilical vesicle. it is connected to enteron of embryo by a slender yolk stalk.