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 | Visitor | Score | Home | Attendance | Record | Points |
| --- | --- | --- | --- | --- | --- | --- |
| December 3 | Detroit | 1–2 | Pittsburgh | 4116.0 | 7–10–5 | 19.0 |
| December 6 | Pittsburgh | 0–5 | Toronto | 16449.0 | 7–11–5 | 19.0 |
| December 7 | Toronto | 2–3 | Pittsburgh | 7310.0 | 8–11–5 | 21.0 |
| December 10 | Pittsburgh | 2–0 | Los Angeles | 5366.0 | 9–11–5 | 23.0 |
| December 12 | Pittsburgh | 1–4 | Oakland | 4760.0 | 9–12–5 | 23.0 |
| December 14 | Pittsburgh | 1–2 | Boston | 14831.0 | 9–13–5 | 23.0 |
| December 17 | Montreal | 5–2 | Pittsburgh | 6381.0 | 9–14–5 | 23.0 |
| December 20 | Boston | 6–4 | Pittsburgh | 7858.0 | 9–15–5 | 23.0 |
| December 21 | Pittsburgh | 0–4 | Philadelphia | 12423.0 | 9–16–5 | 23.0 |
| December 26 | Pittsburgh | 3–2 | NY Rangers | 17250.0 | 10–16–5 | 25.0 |
| December 27 | Chicago | 3–0 | Pittsburgh | 8746.0 | 10–17–5 | 25.0 |
| December 31 | Montreal | 2–4 | Pittsburgh | 5202.0 | 11–17–5 | 27.0 |
Question:
Which Date has a Visitor of boston?
Answer:
December 20