What does it indicate when someone says they are "thirsty"?

When someone says they are "thirsty," it indicates a need for a drink. Thirst is the body's way of signaling that it requires fluids to maintain hydration and support essential bodily functions. This sensation often arises when the body loses water through activities such as sweating, breathing, or urination, and it serves as a reminder to replenish the fluids necessary for optimal health.

The other options, while related to food and drink, do not capture the essence of what being "thirsty" signifies. For instance, saying someone is "not hungry" touches on the desire for food, which is distinct from the need for hydration. Similarly, stating that someone is "good to eat" or "very tasty" pertains to food quality and preference rather than the physiological cue of thirst. Thus, the most accurate choice that aligns with the meaning of "thirsty" is the indication of needing a drink.