Final answer:
During Franz Liszt's era, the piano became the most prominent instrument, symbolizing Romantic music with its enhanced expressive capabilities and sound.
Step-by-step explanation:
During the time of Franz Liszt, the most prominent instrument that emerged was the piano. Advancements in construction and mechanics allowed the piano to have a more powerful, resonant sound and to be played with greater expressivity and control. Liszt, along with other virtuosos like Niccolò Paganini, became the first 'pop star' personalities, captivating audiences with their performances. The industrial revolution led to improvements in the manufacture of musical instruments, especially in the mechanics of woodwinds, brass, and stringed instruments. Nevertheless, it was the piano that truly came to symbolize the Romantic era in music, with its dynamic range and expressive capabilities, making it a preferred choice for both composers and virtuosic performers of the time.