user: Question: Who won best amiga demo when Tribes ( Pulse & Melon Dezign) won best pc demo?
Columns: ['Year', 'Amiga demo', 'PC demo', 'C64 demo', 'Amiga intro', 'PC intro']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1991', 'Odyssey (Alcatraz)', 'N/A', 'Brutality (Light)', 'N/A', 'N/A']
SQL:

assistant: SELECT "Amiga demo" FROM "Table" WHERE "PC demo" = 'Tribes ( Pulse & Melon Dezign)';