单选题：What is wrong in the following code?
What is wrong in the following code?
```
vector v;
v[0] = 2.5; @[C](2)
```
A. The program has a compile error because there are no elements in the vector.
B. The program has a compile error because you cannot assign a double value to v[0].
C. The program has a runtime error because there are no elements in the vector.
D. The program has a runtime error because you cannot assign a double value to v[0].
A.The program has a compile error because there are no elements in the vector.
B.The program has a compile error because you cannot assign a double value to v[0].
C.The program has a runtime error because there are no elements in the vector.
D.The program has a runtime error because you cannot assign a double value to v[0].
答案：C
```
vector
v[0] = 2.5; @[C](2)
```
A. The program has a compile error because there are no elements in the vector.
B. The program has a compile error because you cannot assign a double value to v[0].
C. The program has a runtime error because there are no elements in the vector.
D. The program has a runtime error because you cannot assign a double value to v[0].
A.The program has a compile error because there are no elements in the vector.
B.The program has a compile error because you cannot assign a double value to v[0].
C.The program has a runtime error because there are no elements in the vector.
D.The program has a runtime error because you cannot assign a double value to v[0].
答案：C