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:
| Date | Tournament | Winning score | Margin of victory | Runner(s)-up |
| --- | --- | --- | --- | --- |
| 16 Sep 1984 | World Seniors Invitational | −7 (69-69-69-74=281) | 1 stroke | Arnold Palmer |
| 9 Dec 1984 | General Foods PGA Seniors' Championship | −2 (67-73-74-72=286) | 3 strokes | Don January |
| 17 Mar 1985 | The Vintage Invitational | −7 (69-73-69-69=280) | 1 stroke | Billy Casper , Arnold Palmer |
| 31 Mar 1985 | American Golf Carta Blanca Johnny Mathis Classic | −11 (70-64-71=205) | 1 stroke | Don January |
| 5 May 1985 | MONY Senior Tournament of Champions | −4 (70-70-71-73=284) | 3 strokes | Don January , Dan Sikes |
| 9 Jun 1985 | The Champions Classic | −6 (68-72-70=210) | 2 strokes | Billy Casper , Jim Ferree |
| 16 Jun 1985 | Senior Players Reunion Pro-Am | −14 (68-66-68=202) | 2 strokes | Lee Elder |
| 21 Jul 1985 | MONY Syracuse Senior's Classic | −9 (70-64-70=203) | 2 strokes | Miller Barber , Gene Littler |
| 18 Aug 1985 | du Maurier Champions | −13 (64-70-69=203) | 1 stroke | Ben Smith |
| 15 Sep 1985 | United Virginia Bank Seniors | −9 (69-69-69=207) | 4 strokes | George Lanning |
| 20 Oct 1985 | Barnett Suntree Senior Classic | −9 (70-68-69=207) | 1 stroke | Charlie Sifford |
Question:
Which Date has a Margin of victory of 4 strokes?
Answer:
15 Sep 1985