user: Question: Which team was the opponent on week 15?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Game site', 'Record', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 9, 1960', 'at Boston Patriots', 'W 13–10', 'Boston University Field', '1–0', 21597.0]
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Week" = 15.0;