单选题：若有以下说明:

若有以下说明:
```
int a[12]={1,2,3,4,5,6,7,8,9,10,11,12};
char c='a',d,g;
```
则数值为4的表达式是( )

@[D](2)

A. a[g-c]
B. a[4]
C. a['d'-'c']
D. a['d'-c]



A.a[g-c]
B.a[4]
C.a['d'-'c']
D.a['d'-c]


答案：D