Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Team | Coach | Home Ground | Location | Founded |
| --- | --- | --- | --- | --- |
| The Cove SC | Danny Graystone | Club Cove | Hallett Cove | 1983 |
| Gawler | John Duthie | Karbeethan Reserve | Evanston | 1978 |
| N.A.B | Unknown | Athelstone Recreation Reserve | Athelstone | 1989 |
| Northern Demons | Anthony Brevi | Byrne Park | Port Pirie | 1951 |
| Salisbury United | Unknown | Steve Jarvis Park | Salisbury | 1954 |
| Seaford | Ben Dale | Karingal Reserve | Seaford | 1970 |
| South Adelaide | Aldo Maricic | O'Sullivan Beach Sports Complex | O'Sullivan Beach | 1997 |
| Sturt Lions FC | Alan Paice | A A Bailey Recreation Ground | Clarence Gardens | 2011 |
| Western Toros | Leigh Mathews | Pennington Oval | Pennington | Unknown |
| West Adelaide | Ross Aloisi | Kingston Gardens | Adelaide | 1962 |
Question:
Which team has an unknown coach and location of Athelstone?
Answer:
N.A.B