Final answer:
Vomiting, or emesis, is the forceful expulsion of food through the mouth. It is often caused by irritants in the digestive tract and is regulated by the medulla.
Step-by-step explanation:
The word 'vomit' is most closely matched with the option 'a) spew out or up' because vomiting refers to the forceful expulsion of food through the mouth. When an irritant affects the digestive tract, such as a virus or bacteria, it can trigger vomiting. This process is regulated by the medulla in the brain and is caused by strong contractions of the stomach muscles.