Which product innovation most dramatically increased personal ownership of religious texts in the 20th century?

The publishing of religious texts has evolved dramatically over centuries, from hand-copied manuscripts to mass-produced books. In modern times, certain publishing innovations have transformed how people access and engage with sacred writings. This trivia question explores a significant product development that revolutionized the way religious texts became accessible to everyday practitioners across multiple faith traditions.

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

The introduction of paperback religious texts with affordable pricing models
Limited edition leather-bound collector versions with gold-leaf pages
Subscription services delivering monthly religious commentary
Audio recordings of sacred texts on vinyl records and cassettes