这台电压表/伏特计如此灵敏，可以测量出电压的微小变化。This is such（）sensitive voltmeter that it can measure the slightest changes in voltage.

这台电压表/伏特计如此灵敏，可以测量出电压的微小变化。This is such（）sensitive voltmeter that it can measure the slightest changes in voltage.
A.a
B.an
C.the
D./
正确答案：a