Final answer:
Wolfgang Amadeus Mozart began composing music as a toddler, showcasing his extraordinary talent from a very young age, distinctively during the Classical period.
Step-by-step explanation:
The composer who began composing music while still a toddler was c) Wolfgang Amadeus Mozart. Mozart showed prodigious ability from his earliest childhood in Salzburg. Already competent on keyboard and violin, he composed from the age of five and performed before European royalty.
He was one of the few composers during the Classical period who began demonstrating his considerable musical talent at a very young age. While other composers like Ludwig van Beethoven, Franz Schubert, and Johann Sebastian Bach were also influential and composed memorable music, it was Mozart who was known for his early start in music.