For this iterator which of the following is correct? If correct what does the expression produce?

Suppose we have the following definition:
```
vector vec;
// use push_back to put 10 values into vec here.
vector::iterator itr1, itr2,itr3;
itr1 = vec.begin();
itr2 = vec.begin() + 5;
itr3 = vec.end();
```

a) ```
*iter1
```
b) ```
itr2[3]
```
c) ```
itr + 3
```
>>>there is no itr, Do you mean itr3?
d) ```
itr – 3
```
e) ```
itr3 – itr1
```
(if valid, what does this produce?)
>>You asked for what is produced for all of them in intro to question

Suppose we have the following definition:
```
vector vec;
// use push_back to put 10 values into vec here.
vector::iterator itr1, itr2,itr3;
itr1 = vec.begin();
itr2 = vec.begin() + 5;
itr3 = vec.end();
```

a) ```
*iter1
```
b) ```
itr2[3]
```
c) ```
itr + 3
```
>>>there is no itr, Do you mean itr3?
d) ```
itr – 3
```
e) ```
itr3 – itr1
```
(if valid, what does this produce?)
>>You asked for what is produced for all of them in intro to question