Step 1: We must identify the statement that correctly reflects the labour protections written into the Factories Act.
Step 2: A core rule of the Act is the bar on employing any child below the age of 14 in a factory, while those between 15 and 18 are adolescents who require a certificate of fitness to work.
Step 3: On hours, the Act caps weekly work at 48 hours and daily work at 9 hours, with a mandatory rest break, so any claim of 72 or 82 hours a week directly contradicts the statute.
Step 4: The notion that a child under 14 may take on heavy work for higher pay is plainly unlawful, leaving the statement that under-14 children are not employed under the Act as the only correct choice.
\[\boxed{\text{Children under 14 years are not employed under the Factory Act}}\]