41. Under a provision of the Constitution that was never applied. Congress has been required to call a conven­tion for considering possible amendments to the document when formally asked to do it by the legisla­tures of two-thirds of the states. ?????

(A) was never applied, Congress has been required to call a convention for considering possible amendments to the document when formally asked to do it

(B) was never applied, there has been a requirement that Congress call a convention for consider­ation of possible amendments to the document when asked to do it formally

(C) was never applied, whereby Congress is required to call a convention for considering possible amendments to the document when asked to do it formally

(D) has never been applied, whereby Congress is required to call a convention to consider possible amendments to the document when formally asked to do so

(E) has never been applied. Congress is required to call a convention to consider possible amend­ments to the document when formally asked to do so

为什么D 的“Whereby”不行，没理解它的解释， produce sentence fragments