Given the Following Code Snippet, What Should We Change to Have

Multiple Choice

Given the following code snippet, what should we change to have 26 alphabet characters in the string str? String str = "";
For (char c = 'A'; c < 'Z'; c++)
{
Str = str + c;
}

A) int c = 'A'
B) str = c + str;
C) c <= 'Z'
D) Must change to use a do loop