Phoenix India Research and Development Group launched the first biogas fuelled public bus in India with a flat fare of just Rs 1 in which city?

Introduction / Context:
Environment friendly transportation initiatives are often highlighted in general knowledge sections because they link technology, public policy, and sustainable development. The launch of a biogas fuelled bus with a very low flat fare is a notable example. This question asks about the Indian city where Phoenix India Research and Development Group introduced such an innovative bus service with a fare of just one rupee.

Given Data / Assumptions:

The bus is fuelled by biogas, a renewable energy source.
The project was launched by Phoenix India Research and Development Group.
The flat fare on this bus was set at Rs 1 for passengers.
We are to identify the city where this bus service was introduced.

Concept / Approach:
This question tests awareness of environmental and transport related current affairs. Candidates need to recall which city was associated with this biogas bus initiative and the symbolic one rupee fare. The correct association is with Kolkata, a metropolitan city that has been part of several pilot projects in public transportation.

Step-by-Step Solution:
Step 1: Note that the bus was biogas fuelled and offered a flat fare of Rs 1. Step 2: Recall which city was mentioned in news reports about this project by Phoenix India Research and Development Group. Step 3: Match that remembered city with the options and choose Kolkata.

Verification / Alternative check:
News articles and environmental awareness reports discussing biogas powered transport initiatives mention that the first such bus with a one rupee fare was launched in Kolkata. Cross checking across multiple sources such as newspapers and current affairs compilations confirms this link and verifies the correctness of option A.

Why Other Options Are Wrong:
Bengaluru is known for several technology experiments but was not the city for this specific biogas bus project, so option B is incorrect.
Chennai has its own transport initiatives but did not host the Phoenix India biogas bus with a one rupee fare, so option C is not right.
Mumbai is a major metropolis but was not the launch city for this scheme, which makes option D incorrect.

Common Pitfalls:
Candidates may guess based only on the reputation of a city for innovation, such as Bengaluru or Mumbai, instead of recalling the specific news item. Others may confuse this biogas project with unrelated experiments like electric buses or metro projects in different cities. Careful reading of reliable current affairs sources and connecting the one rupee fare with Kolkata helps avoid such mistakes.

Final Answer:
The first biogas fuelled bus with a flat fare of Rs 1 was launched in Kolkata.