Which one of the following is useful for controlling the flow of traffic on the roads?

Assertion: In big cities electronic signals are used.

Reason: The trafiic is regulated very easily with the help of red, orange and green lights in these signals.

The second signal is intended to stop vehicles coming from the 

The first signal comes under

The colour lights used in the electronic signals are 

How many types of manual signals are used?

For beckoning vehicles approaching from the front, the signal which is used is

In big cities, the traffic is controlled with the help of

Railway level crossing consists of

The carelessness of the drivers causes