Indian fertilizer industry (gas-based plants): Among the following pairs, identify the states that host two well-known gas-based fertilizer plants (using natural gas/NG as feed-stock).

Introduction:
Gas-based fertilizer plants produce ammonia and urea using natural gas as the primary feed and fuel, leveraging the high hydrogen content and clean combustion. In India, plant siting correlates with gas availability and pipeline connectivity. This question checks recognition of major gas-based clusters by state.

Given Data / Assumptions:

• Focus on states, not specific plant names.
• Historical and present-day siting favors western/central gas corridors.
• Pairs provided include plausible but incorrect combinations.

Concept / Approach:
Gujarat has significant petrochemical and fertilizer capacity associated with gas terminals and networks (e.g., Hazira). Madhya Pradesh hosts large gas-based units (e.g., at Vijaipur), supplied via national gas pipelines. The pair Gujarat–Madhya Pradesh is a classic textbook answer to “two gas-based fertilizer plants are located in …”.

Step-by-Step Solution:
Identify gas-rich/connected states: Gujarat and Madhya Pradesh.Exclude pairs that include coal-centric or less gas-linked states for such plants.Select “Gujarat and Madhya Pradesh”.

Verification / Alternative check:
Industry directories and historical overviews repeatedly cite Hazira (Gujarat) and Vijaipur (Madhya Pradesh) as archetypal gas-based ammonia-urea centers.

Why Other Options Are Wrong:

• Maharashtra and Gujarat: While both have relevant industry, the canonical pair in standard questions is Gujarat–Madhya Pradesh.
• Maharashtra and Orissa; Jharkhand and Chhattisgarh; Tamil Nadu and Rajasthan: These pairs do not represent the classic duo of gas-based hubs referenced in traditional exam keys.

Common Pitfalls:
Mixing coastal refinery locations with gas-based fertilizer siting; the decisive factor is gas feedstock, not merely industrial activity.

Final Answer:
Gujarat and Madhya Pradesh