Final answer:
Without additional context or information related to Sergio's building and its residents, it is not possible to determine who pushed a folded grocery cart from the choices provided.
Step-by-step explanation:
The information provided does not include details about Sergio's building or the individuals who might have lived there, including who pushed a folded grocery cart. Therefore, based on the provided text excerpts, it is not possible to confirm whether the person who lived in Sergio's building and pushed a folded grocery cart was A) Mrs. Salinger, B) Eliza, C) Naheed, or D) The janitor. To answer accurately, one would need more context or information specifically related to the question.
Without additional context or information related to Sergio's building and its residents, it is not possible to determine who pushed a folded grocery cart from the choices provided.