On average, how much air do humans breathe in a day?

The correct choice is based on the average volume of air a person breathes per day. An adult typically breathes in about 6 to 10 liters of air per minute at rest. Over the course of a day, this amounts to approximately 8 to 10 cubic meters of air, which translates to around 35 pounds or slightly more.

When considering the physical attributes of air, the density of air is approximately 1.225 kg/m³ at sea level. By converting the typical daily respiratory volume, it equates to a weight of around 35 pounds. Thus, this figure accurately represents the average volume of air inhaled by humans throughout a day, making it the most logical and scientifically supported answer.

Other choices, such as 3 to 4 pounds, significantly underestimate the amount of air inhaled, while 37 pounds slightly overestimates the weight. The option regarding 1,600 cubic feet is related to volume but does not directly correspond to the more common measurements of daily air intake in terms of weight. Hence, the estimate of 35 pounds stands out as the most accurate representation.