What is the value in n after line 4 is run?

Use the following code to answer the next set of questions. Assume all needed files are included.

1.
```
string s, t;
```

2.
```
s = “Get up and go to school!”;
```

3.
```
t = “NO!”;
```

4.
```
int n = s.size();
```

5.
```
int w = s.at(3);
```

6.
```
int x = s.at(12);
```

7.
```
s += t;
```

8.
```
cout << s;
```

A. 23
B. 24
C. 3
D. -1

B. 24