Final answer:
A preterm infant is defined as a) one born before 37 complete weeks of pregnancy, which includes infants with oxygenation problems and a lack of subcutaneous fat.
Step-by-step explanation:
The newborn infant in the question has been described as preterm with oxygenation problems and lack of subcutaneous fat. According to the gestational age classifications, a preterm infant is one born before 37 completed weeks of pregnancy.
Therefore, the correct assessment of the gestational age of the preterm infant would be 'a. 0 to 37 complete weeks of pregnancy'. Preterm infants have an increased risk of complications due to immature organ systems, and intensive medical care is often required, especially for those born before 26 weeks of gestation.