Two signs used in a _________________ alert drivers to children who might dart out into the street without looking.

The correct option is "school zone" because signs specifically designed for school zones are put in place to increase awareness of the presence of children in the area, particularly during times when they are arriving at or leaving the school. These signs serve as a warning to drivers to reduce their speed and be vigilant for children who may unexpectedly enter the roadway, especially since children are often distracted and may not be fully aware of the traffic around them.

Signs in school zones are typically accompanied by additional measures, such as flashing lights or crossing guard direction, to further ensure safety. While residential areas and playground zones may also have their own specific signs pertaining to safety and speed, the school zone signs are explicitly intended to address the presence of children in a scenario that can be particularly hazardous—namely, near educational institutions where children are likely to be present during peak entry and exit times.