Which of the following identifiers can be used as a variable name?

Which of the  following identifiers can be used as a variable name?

Letters:

A   B   C   D   E   F   G   H   I   J   K   L   M

N   O   P   Q   R   S   T   U   V   W   X   Y   Z

a   b   c   d   e   f   g   h   i   j   k   l   m

n   o   p   q   r   s   t   u   v   w   x   y   z

Digits:

0   1   2   3   4   5   6   7   8   9

[A] Sample_Program

Underscore is not a letter.

[B] Variable

Valid.

[C] <Counter>     

Identifiers must not contain any special symbols.

Special symbols:

+   -   *   /
.   ,   :   ;
=   <>   <   <=   >   >=
:=   ..   ^   '
(   )   [   ]   {   }

[D] TYPE

No reserved words.

Reserved words:
and   array   begin   case   const   div   do
downto   else   end   file   for   function
goto   if   in   label   mod   nil   not   of   or
packed   procedure   program   record   repeat
set   then   to   type   until   var   while   with

[E] über

Umlauts are not letters.