Final answer:
The subject of this question is Physics and it is applicable to High School level.
Step-by-step explanation:
This question can be related to the concept of dissolving process in physics. The process of making hot drinks in a vending machine involves the dissolving of various substances like milk and sugar in hot water. When you choose a hot drink, the machine asks if you want milk or sugar and adds them if desired before dispensing the drink. This process of dissolving substances in a liquid can be studied in physics.