Final answer:
The nurse should obtain a practitioner's order for a bilirubin level to assess the level of bilirubin in the infant's blood.
Step-by-step explanation:
When assessing an infant who was born at home 24 hours ago and exhibits slight jaundice of the face and trunk, the community health nurse should obtain a practitioner's order for a bilirubin level (Option B). This is important to assess the level of bilirubin in the infant's blood and determine if it is within a safe range or requires further intervention.