In which of Dante's works is the "dolce stil novo" literary style first presented?

Explanation

Dante introduced the "dolce stil novo" style in his work "Vita Nuova," where he explores this refined poetic technique. The other texts, such as "The Convivio" and "De Vulgari Eloquentia," focus on different literary themes, while "Eclogues" and "La Divina Commedia" are unrelated to the introduction of this style.