Option A is correct because the provided context explicitly lists both the flash method (HTST) and Ultra-High Temperature (UHT) as methods of pasteurisation. The text describes pasteurisation as a process used in the food and dairy industry to kill pathogenic microorganisms in milk, detailing that HTST involves heating at 72°C for 15 seconds and UHT involves heating at 140–150°C for 1–3 seconds.