Final answer:
A term infant in gestational age assessment is indicated by the presence of plantar creases on at least two-thirds of the sole. This is characteristic of full-term infants, whereas other options may suggest prematurity or are insufficient as standalone indicators.
Step-by-step explanation:
The term infant indicates a human being between birth and the first birthday, and the initial assessment right after birth is critical in determining their well-being. The Apgar test is administered immediately after birth to assess key health indicators. One of the physical characteristics indicative of a term infant in gestational age assessment is the presence of plantar creases on at least two-thirds of the sole, which corresponds to an infant at full term. Options featuring opaque skin, minimal ear cartilage, and a large amount of lanugo would typically indicate prematurity, while heart rate assessment alone, without additional context, is insufficient to determine gestational age.