Final answer:
The Factory Act of 1833 made it illegal for children under 9 to work and reduced working hours for children aged 9-12 and 13-17. It was enforced by the British government.
Step-by-step explanation:
The act that made it illegal for children under 9 to work and reduced working hours for children aged 9-12 to less than 8 hours, and for children aged 13-17 to less than 12 hours, was the Factory Act of 1833. This act was enforced by the British government.