A

Each horizontal small square on the WHO partograph equals 30 minutes, not 1 hour; the bold vertical lines mark 1-hour intervals. The alert and action lines are drawn 4 hours apart, recording begins once the cervix is 4 cm dilated (active phase), and a woman whose labour curve crosses the alert line should be referred or closely monitored at a higher-level facility [Lavender 2018, PMID 30080256].