2岁男孩，因智能低下查染色体核型为46，XY，-14，+t（14q21q），查其母为平衡易位染色体携带者，核型应为（）。

A.45，XX，-14，-21，+t（14q21q）

B.45，XX，-15，-21，+t（15q22q）

C.46，XX

D.46，XX，-14，+t（14q21q）

E.46，XX，-21，+t（14q21q）

"But the doctor can't use just anyone's blood. The donor's blood has to be of a type that won't be destroyed by your blood." This statement means that______.

A．the doctor can't use the donor's blood because your blood can destroy this

B．the doctor has to choose a donor whose blood can not be destroyed by your blood

C．the doctor has to choose a certain type of blood from a donor whose blood will not be destroyed by yours

D．the doctor can choose a certain type of blood from any donors