By when are surfactant levels usually adequate to give effective lung compliance?

1. Type II cells begin secreting surfactant in small amounts from about week 20. 2. Larger amounts follow as growth and maturation continue from week 24 to term. 3. Surfactant levels are not generally adequate to create effective lung compliance until about the eighth month of pregnancy. 4. So early secretion and adequate secretion are two different milestones, months apart. 5. The fourth option is wrong because a term newborn inflates its lungs on the first breath. 6. The fourth and sixth month options confuse the start of secretion with the point at which it becomes sufficient. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.7 Embryonic Development of the Respiratory System_