A peculiar feature of the embryonic mammalian circulatory system is that in the area of the heart the cells adhere to one another, beating in unison and adopting specialized orientations exclusive of one another.

(A) beating in unison and adopting

(B) they beat in unison while adopting

(C) beat in unison, and adopt

(D) beating in unison yet adopting（D）

(E) even though they beat in unison and adopt

请问A和C错误原因是不是因为没有表达出转折的意思？D选项在原文中做什

么成份？伴随状态？多谢！