Final answer:
Lung maturity is the most critical determinant of fetal maturity for extrauterine survival, as it allows the newborn to breathe independently after birth.
Step-by-step explanation:
The most extreme determinant of fetal maturity for extrauterine survival is a) Lung maturity. The development of the lungs and the production of surfactant are critical for the newborn to breathe independently outside the uterus. Without adequate lung maturity and surfactant production, a premature newborn may suffer from respiratory distress syndrome and require intensive medical interventions such as surfactant replacement therapy, supplemental oxygen, or CPAP to survive. Although factors like gestational age, weight, and head circumference play significant roles in fetal development, lung maturity is imperative for a fetus's ability to survive immediately after birth.