K Using a while-loop, loop over the indices of the string my_str O a. index = 0 while index < len(my_str): print(my_str[index]) index + = 1 O b. index = 0 while index <= len(my_str): print(my_str[index]) index + = 1 O c. index = 1 while index <= len(my_str): print(my_str[index]) index + = 1 O d. for char in my_str: print(char) = "Hello": ~