The answer to this question would be: 2:1
A lung is called mature if it has surfactant that will reduce the surface tension of the alveolus. Lower surface tension will decrease the chance of respiratory distress. Letichin is the phospholipid that makes surfactant so it can be used to estimate the amount of the surfactant. Ratio 2:1 would indicate mature lungs with a low chance of RDS.
