Question

what is a reliable way to ensure potentially hazardous/high - risk foods are thoroughly cooked?
check the internal colour
use a probe thermometer
check juices are clear
all of the above

Explanation:

Checking internal color and juice clarity can be misleading as some bacteria may not be visible. A probe thermometer is a scientific and reliable tool to measure the internal temperature of food. If the food reaches a certain safe temperature (depending on the type of food), it is likely to be thoroughly cooked and free from harmful bacteria.

Answer:

Use a probe thermometer.