Which pioneering language learning app first introduced a 'freemium' subscription model with a 'streak' feature to boost user retention through gamification?

Language learning has transformed dramatically in the digital age. Modern subscription-based language platforms use sophisticated algorithms and linguistic research to optimize learning. These apps employ various techniques from spaced repetition to natural language processing to help users acquire new languages. But how much do you know about the business models behind these linguistic innovations? Test your knowledge of language learning product development!

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Duolingo
Babbel
Rosetta Stone
Memrise