The major mode of public transport within cities of Punjab is:

Metro Rail
Auto-rickshaws
Taxis
Trams

The correct answer is: b) Auto-rickshaws.

Auto-rickshaws are a three-wheeled motorized vehicle that is commonly used as a taxi in India. They are a popular mode of transportation in Punjab, as they are relatively inexpensive and can easily navigate through the city’s narrow streets.

Metro Rail is a rapid transit system that is currently under construction in Punjab. It is expected to be completed in 2023 and will connect the major cities of the state.

Taxis are also available in Punjab, but they are more expensive than auto-rickshaws. They are a good option for longer journeys or for traveling to places that are not well-served by public transportation.

Trams are not a common mode of transportation in Punjab. There is one tram line in the city of Amritsar, but it is not a major mode of transportation.

In conclusion, the major mode of public transport within cities of Punjab is auto-rickshaws. They are a popular and affordable option for getting around the city.