Final answer:
By the age of 11, Wolfgang Amadeus Mozart had already composed his first opera, showcasing his status as a musical prodigy.
Step-by-step explanation:
By the age of 11, Wolfgang Amadeus Mozart had composed his first opera. Mozart was a musical prodigy who started composing at a very young age. While several musicians have made significant contributions to the evolution of music, Mozart's achievements as a child are particularly notable. His early compositions demonstrate a mastery of form and melody. To give a comparison, another noteworthy composer, Arnold Schoenberg, dramatically changed the landscape of music during his time by inventing a twelve-tone scale and experimenting with atonality, which was a deviation from the traditional musical scales used since the Renaissance. However, it is Mozart's accomplishments at a young age that answer this specific question.