India and Bangladesh are linked by a passenger rail service between Kolkata and Dhaka that symbolises friendship between the two countries. Which of the following is the only train that runs directly between Kolkata and Dhaka?

Introduction / Context:
This question concerns international rail connectivity and India's relations with its neighbour Bangladesh. Passenger train services between Kolkata and Dhaka have important diplomatic and economic significance. The name of the train that connects these two cities is frequently asked in general knowledge examinations.

Given Data / Assumptions:

• The route is between Kolkata in India and Dhaka in Bangladesh.
• The question asks for the only train that runs directly between these two cities.
• The options include several names that sound like they could relate to friendship or to Bangladesh.
• Only one name corresponds to the actual established train service between Kolkata and Dhaka.

Concept / Approach:
The key concept is recall of factual information about named international train services. The well known passenger train between Kolkata and Dhaka is called "Maitree Express". The word "Maitree" means friendship, reflecting the friendly relations between the two countries. Other option names like Dosti Express or Bangla Express may sound plausible but do not correspond to this specific India Bangladesh service.

Step-by-Step Solution:
Step 1: Identify that the question is about a direct train between Kolkata and Dhaka. Step 2: Recall from current affairs that India and Bangladesh reintroduced and developed the Maitree Express on this route. Step 3: Examine the options and note that "Maitree" clearly conveys friendship, matching the spirit of bilateral cooperation. Step 4: Recognise that Dosti Express and Bangla Express are not standard names of this route as per standard railway and GK references. Step 5: Select Maitree Express as the only correct answer.

Verification / Alternative check:
You can verify this by recalling news photographs and reports about the inauguration and operations of the Maitree Express, which often highlight passengers travelling between Kolkata and Dhaka for work, tourism and family visits. Standard general knowledge books and railway awareness notes also list Maitree Express as the train running on the Kolkata Dhaka route. This repeated mention in multiple sources confirms that Maitree Express is the correct answer.

Why Other Options Are Wrong:
Dosti Express sounds similar to a friendship themed name, but it is not the official name of the Kolkata Dhaka train service.
Bangla Express may suggest a link to Bangladesh, yet there is no widely recognised international passenger service with this name connecting Kolkata and Dhaka.
Padma Express is associated with Bangladesh Railways but is not the designated Kolkata Dhaka train under Indian exam oriented general knowledge.
Ganga Sagar Express is the name of another train operating on a different route within India and does not serve as the Kolkata Dhaka international passenger service.

Common Pitfalls:
The main pitfall is to be misled by options that contain words like "Dosti" or "Bangla", which also suggest friendship and Bangladesh. Exam setters deliberately create such distractors. To avoid confusion, you should fix in your memory the exact name "Maitree Express" as the symbolic train of India Bangladesh friendship on this route. Associating "Maitree" with official diplomatic phrasing helps strengthen this memory.

Final Answer:
The only train that runs directly between Kolkata and Dhaka is the Maitree Express.