Final answer:
Mozart's Piano Concerto No. 23, known for its elegance and delicacy, is scored for solo piano, which allows for its nuanced expression.
Step-by-step explanation:
Mozart's Piano Concerto No. 23 emphasizes elegance and delicacy, which is probably why he scored his concerto for solo piano. The correct option is d) Solo piano.
The concerto is known for its lyrical melodies and refined character that are perfectly suited for the piano, rather than the more robust sounds of a full orchestra or the piercing tones of solo brass or violin instruments. The piano, being a versatile and expressive instrument, allows for the nuanced and delicate expression that this piece of music requires.