This is your homework, and I'm afraid you have got to pay more attention to what you are doing.
That is not C# code; it's VB instead, so you appear to be trying to get us to do the wrong classes homework...
Since it is homework, I'm not going to just give you an answer, but I'll give you two clues:
1) it's not (d)
2) look at what a For Each loop works on, then examine the possible types.
http://msdn.microsoft.com/en-us/library/vstudio/5ebk1751.aspx[
^] should help.
If you need more help, we will be happy to oblige, but only if you show us that you have done some of the work yourself, but got stuck.