Which linguistic breakthrough significantly improved retail chatbot performance around 2018-2019, enabling them to better understand context in customer conversations?

In the intersection of linguistics and retail technology, chatbots have transformed customer service experiences. These AI-powered assistants leverage natural language processing to understand customer queries and provide personalized assistance. But how well do you know the history and capabilities of these linguistic retail innovations? Test your knowledge about the evolution of retail chatbots and the linguistic technologies that power them in this challenging trivia question!

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BERT (Bidirectional Encoder Representations from Transformers)
RNN (Recurrent Neural Networks)
LSA (Latent Semantic Analysis)
Word2Vec embeddings