What nutrient does our body use first

Fat intake does not promote fat use as an energy source. Carbs are used first and if the carb calories eaten are sufficient, The excess fat calories in the diet go directly to fat storage. Fat also gives less fullness signals to the brain. (Protein gives the most followed by carbs and fat)

relationship between pressure and air volume and led to the understanding of how respiration works; i believe this is the correct answer ; /// good luck