Some apartments of the early 1900s were known as “dumbbell tenements” because they had

Dumbbell tenements were built with narrow air shafts that made the buildings resemble dumbbells from above. The shafts were intended to provide light and ventilation, but they were often too small to work well, leaving many apartments with few windows and poor ventilation. The correct choice is “few windows and no ventilation.”

AI-written and checked against the verified answer.