Which innovation in book cover design during the 20th century most significantly transformed the publishing industry's approach to product packaging?

Book cover design is a fascinating intersection of literature and visual marketing. Throughout publishing history, cover designs have evolved dramatically to capture reader attention and communicate genre expectations. This poll tests your knowledge about the strategic shifts in book packaging that have influenced consumer purchasing decisions in the literary marketplace. See if you can identify the major turning point that revolutionized how publishers approached cover design for mass market books.

This is a live public trivia poll on AIPolls.Net. Vote and see real-time results.

The introduction of dust jackets on hardcover books in the 1920s
The development of paperback covers with bold graphics in the 1930s-40s by Penguin and Pocket Books
The rise of minimalist text-only covers in the 1970s modernist movement
The implementation of embossed foil lettering techniques in the 1980s