Which condition is assessed by checking the infant’s ability to breathe with nostrils occluded?

The correct answer is choanal atresia, which is a congenital condition in which one or both nasal passages are blocked or narrowed due to abnormal tissue formation. Assessing an infant's ability to breathe with the nostrils occluded is a specific test used to evaluate this condition. If an infant has choanal atresia, occluding the nostrils will significantly impede airflow, resulting in difficulty breathing. This is because infants primarily breathe through their noses, so any blockage would immediately be apparent when normal nasal breathing is hindered.

In contrast, the other conditions listed do not primarily present with difficulty breathing when the nostrils are occluded. Congenital laryngeal stridor usually demonstrates stridor or noisy breathing due to issues within the larynx rather than nasal obstruction. Tracheoesophageal fistula involves abnormal connections between the trachea and esophagus, which leads to feeding difficulties and possible respiratory issues, but it is assessed through different clinical signs and symptoms. Respiratory distress syndrome is typically related to issues with lung maturity and surfactant deficiency in premature infants, leading to respiratory difficulties that are not influenced by nasal passage occlusion.