What is the estimated tidal volume for adults?

The estimated tidal volume for adults, which refers to the amount of air inhaled or exhaled during a normal breath, is typically around 6-8 mL per kilogram of body weight. For an average adult weighing around 70 kg, this translates to approximately 420-560 mL per breath. When considering breathing rates, if you multiply that by a normal respiratory rate (typically about 12-20 breaths per minute), it can indeed be estimated that adults breathe in about 5-7 liters of air per minute overall. This aligns with the correct choice, as it correctly reflects the average tidal volume for adults within a practical range, making it the most suitable option among the choices provided.