The Mannheim school played a pivotal role in the development of the symphony during the 1740s and 1750s with innovative techniques and expressive styles. Unlike Venice, Paris, or London, Mannheim's advancements seemed particularly avant-garde at the time. Key figures like Johann Stamitz were crucial in this evolution. ;
The symphony was developing in an avant-garde way in Mannheim during the 1740s and 1750s, thanks to the innovative techniques of composers like Johann Stamitz. Unlike cities like Venice, Paris, or London, Mannheim focused on new expressions in orchestral music, particularly through dynamic changes and richer textures. Therefore, the correct answer is C. Mannheim.
;