根据MRI表现考虑为何种疾病是()

A．羊瘙痒病

B．皮质一纹状体-脊髓变性

C．进行性多灶性白质脑病

D．亚急性硬化性全脑炎

E．进行性风疹全脑炎

I didn't go to the barbecue last night ______ I had something more important to do. [ ]

A. so

B. if

C. because

D. but