In an urban transit bus, what is the 'Blind Area' (zona ciega) directly behind the vehicle, and how should reversing maneuvers be executed?

1. There are no blind spots behind a modern bus
2. The area directly behind the bus is a massive blind zone; reversing on city streets is prohibited except in terminals/depots and must always be guided by ground personnel (señalero / banderillero)
3. Reversing should be done at 40 km/h with the horn sounding
4. The driver may reverse without looking if mirrors are clean