Final answer:
For an infant with choanal atresia requiring 28% supplemental oxygen, a Venturi mask is the appropriate device as it can deliver a precise oxygen concentration without using nasal passages.
Step-by-step explanation:
An infant with choanal atresia, a condition where the back of the nasal passage is blocked, typically requires a delivery device for supplemental oxygen which avoids nasal passages due to the obstruction. Looking at the options provided: (a) Nasal cannula, (b) Venturi mask, (c) Non-rebreather mask, and (d) High-flow nasal cannula, the Venturi mask is the most suitable choice for delivering a precise oxygen concentration (28%) without using the nasal passages. A Venturi mask can deliver the required oxygen through a mask that covers the mouth and does not rely on nasal airflow, making it the appropriate choice in the context of choanal atresia.