At what times are yellow lanterns displayed in the subway to indicate employees working on the tracks?

The display of yellow lanterns in the subway is an important safety measure that indicates to train operators and passengers alike that maintenance or repair work is occurring on the tracks. In this case, the correct answer reflects specific peak times when the likelihood of workers being present on the tracks increases, thus necessitating the yellow lanterns for heightened safety awareness.

Yellow lanterns are typically displayed during weekdays between 7:30 AM and 9:30 AM as this period aligns with the start of daytime operations when many employees are engaged in maintenance. This targeted timing is crucial because it helps train operators to prepare and approach these areas with increased caution during high-traffic hours when trains are more frequently traveling through the subway system.

The other options suggest either a broader or less precise application of the yellow lanterns, such as being on all weekends, being displayed after certain hours, or at any time of the day. These options do not capture the specific operational policies that focus on specific times during weekdays when employee presence on the tracks is most common, which makes option B the most accurate choice.