Which natural language processing breakthrough, first commercially implemented around 2011, dramatically improved voice assistants' ability to understand spoken retail commands?

The retail tech landscape has been revolutionized by voice assistants that can understand and respond to natural language. Behind these innovations are sophisticated linguistic algorithms and machine learning models that have evolved dramatically over the past decades. This poll explores a pivotal development in computational linguistics that made today's voice commerce possible. Test your knowledge about the technology enabling millions of voice-based retail transactions daily!

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

Deep neural networks for speech recognition
Markov chain text prediction
Rule-based grammar systems
Keyword spotting algorithms