Why are customers not always "end use" customers?

After first arriving in new york, charlie parker took a job as a dishwasher at jimmy's chicken shack, where played the piano nightly. listening to his astonishing harmonic restructuring, virtuoso phrasing, and breakneck tempos every night for three months, charlie parker challenged himself to adopt these qualities into his playing, and he continued to practice tirelessly.

Which sentence contains a comma splice? marco rode to school on his bicycle this morning, he arrived an hour early.marco, who enjoys riding his bicycle to school, arrived just before the bell today.marco rode to school on his bicycle on monday, tuesday, and wednesday.marco, who rode to school on his bicycle this morning, arrived an hour early.mark this and returnsave and exit

For the difference command to work, what needs to happen?