user: Question: What is the highest number a Guard from Brophy College Prep wore?
Columns: ['Name', '#', 'Position', 'Height', 'Weight ( lb. )', 'Year', 'Hometown', 'Previous School']
Types: ['text', 'real', 'text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['Gilbert Brown Category:Articles with hCards', 5.0, 'Forward', 'ft6in (m)', 215.0, '2 Senior ( RS )', 'Harrisburg , PA', 'South Kent School']
SQL:

assistant: SELECT MAX("#") FROM "Table" WHERE "Position" = 'Guard' AND "Previous School" = 'Brophy College Prep';