Final answer:
The correct answer is option c) Richard Wagner.
Step-by-step explanation:
Among the composers listed, Richard Wagner is considered the single most important phenomenon in the artistic life of the latter half of the nineteenth century. Wagner's contributions to the world of music were influential and far-reaching, embodying the essence of the Romantic era in music. His innovative transformations in opera and musical thought were pivotal, and with his concept of the 'Gesamtkunstwerk' or 'total work of art' combining music, drama, and visual spectacle, Wagner pushed the boundaries of music and set the stage for modernism.
Wagner was known for his epic operas, complex harmonies, and rich orchestral compositions. His works such as 'The Ring Cycle,' 'Tristan und Isolde,' and 'Parsifal' revolutionized opera and had a lasting impact on the music of his time and beyond. As a progressive, he challenged audiences with his music and his theatrical innovations often caused controversy and excitement in the musical world.
Other Romantic composers, such as Brahms and Tchaikovsky, created famous and beloved works as well, but it was Wagner who most dramatically altered the musical landscape of his time. This is not to say that other composers like Beethoven, who had a foundational influence on the Romantic period, or Mozart, who defined the Classical era, were not important; rather, Wagner's radical ideas and compositions stood out in the latter half of the nineteenth century.