user: Question: Who is the challenge leader that played on 9:30 pm on Wed., Nov. 28?
Columns: ['Date', 'Time', 'ACC Team', 'Big Ten Team', 'Location', 'Television', 'Attendance', 'Winner', 'Challenge Leader']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Tue., Nov. 27', '7:15 pm', 'Virginia Tech', 'Iowa', 'Cassell Coliseum • Blacksburg, VA', 'ESPNU', 5647.0, 'Virginia Tech (95-79)', 'ACC (1-0)']
SQL:

assistant: SELECT COUNT("Challenge Leader") FROM "Table" WHERE "Time" = '9:30 pm' AND "Date" = 'Wed., Nov. 28';