Final answer:
Resting posture, skin appearance, development of plantar creases, and genitalia development are essential aspects in the assessment of a newborn's gestational age.
Step-by-step explanation:
The correct answer is D) Resting posture, skin appearance, development of plantar creases, and genitalia development.
Assessing a newborn's gestational age involves looking at various aspects. Resting posture refers to the position in which the newborn naturally rests. Skin appearance can provide clues about the baby's maturity and overall health. Development of plantar creases refers to the formation of creases on the soles of the baby's feet, which also indicates maturity. Finally, genitalia development can provide additional information about the baby's gestational age.