According to multiple sources, Post-it Notes were test-marketed in four cities in 1977, with the national roll-out following in 1980.Apart from the technicality that the product originally was sold under the name “Press & Peel” (which would be a stretch even if the category were “brands” instead of “inventions”), “C” was the correct answer. Therefore, the contestants should have lost only $80,000 (not $800,000) on the question.