In one song, to portray a character's obsession with the color green, this composer used a constant 16th-note F sharp. In another song, this composer used a running ostinato of left-hand triplets to evoke horses' hooves, and used character-specific ranges to portray four different characters, including a father and son. This composer wrote a piano quintet based on his song Die Forelle, and a symphony with only two completed movements. For 10 points, name this early romantic Austrian composer of "Die Schöne Mullerin," "The Erl-King," and the Trout Quintet.
a) Franz Schubert
b) Ludwig van Beethoven
c) Wolfgang Amadeus Mozart
d) Johannes Brahms