The main reason opera was so appealing to Baroque audiences was A) the grand spectacle and visual effects.
Opera was characterized by its elaborate and ornate staging, which often included complex sets, costumes, and special effects. The use of music, dance, and drama to tell stories in a visually stunning way made opera an exciting and captivating form of entertainment. While the emotional depth of the music, intricate vocal harmonies, and religious themes and narratives were also important aspects of opera, it was the grand spectacle and visual effects that made it so appealing to Baroque audiences.