It is generally believed that teaching is _____ it is a science.

A．an art much as

B．much an art as

C．as an art much as

D．as much an art as

（143-145题共用题干） 男，38岁。因反复左侧头痛半年，加重伴呕吐3天于急诊留观。查体：浅昏迷，双侧瞳孔为左侧3mm，右侧2mm，对光反应迟钝。右侧肢体肌力4级，右侧Babinski征阳性。

未明确诊断应首选的最简洁的检查方法是

A．经颅彩色多普勒超声

B．脑电图

C．头颅MRI

D．头颅X线片

E．头颅CT