To inform the reader that they are specifically talking about something else, another thing that could be informative
The presence absence of facts and data to back up a claim.
2. Can you play A musical instrument
3. Jessica plays THE violin in an orchestra
4.There was A piano in the corner of the room
5.Can you play THE piano
6. Our society is based on A family
7.Martin comes from A large family
Appetite is not linked to (B) physiological hunger.
Where physiological hunger is linked to the need for food, appetite is mostly related to the desire for food.