7. 下列先天性免疫不全症 (primary immunodeficiencies)中,主要以抗體不足或缺乏抗體(antibody deficiency)為特徵之疾病是那一種?
(A) Common variable immunodeficiency
(B) Adenosine deaminase deficiency
(C) Chronic granulomatous disease
(D) Severe combined immunodeficiency
(E) Di George's syndrome