India has expanded grid connected solar power capacity rapidly in recent years. As per official data on installed capacity, which one of the following states is regarded as leading in solar energy generation in the country?

Introduction / Context:
This question belongs to the area of energy and environment related general knowledge. India has made major investments in solar power, and some states have emerged as leaders in installed solar capacity. Knowing which state is at the forefront of solar energy generation is useful for questions on sustainable development and infrastructure.

Given Data / Assumptions:

• The focus is on leading state level solar energy generation in India.
• The term "leading" refers to highest installed solar power capacity based on official figures.
• The options list states that are all important players in the renewable energy sector.
• Only one of these states has consistently been cited as number one in installed solar capacity in recent official data.

Concept / Approach:
Rajasthan has emerged as a top performer in solar power generation because of its vast arid land, high solar radiation and strong policy support. It hosts some of the largest solar parks in the world and has repeatedly been reported as the state with the highest installed solar capacity. Gujarat, Tamil Nadu and others are also major contributors, but Rajasthan has taken a clear lead in utility scale solar projects in many recent assessments.

Step-by-Step Solution:
Step 1: Recall news reports and official renewable energy updates about state wise solar capacity in India. Step 2: Identify Rajasthan as a state with very high solar potential and several mega solar parks such as those in Jodhpur and Jaisalmer regions. Step 3: Compare this with Gujarat and Tamil Nadu, which are also strong in solar energy but are often ranked slightly lower than Rajasthan in total installed capacity. Step 4: Consider that Haryana and Uttar Pradesh are growing markets but have not surpassed Rajasthan in overall installed solar power. Step 5: Therefore, choose Rajasthan as the leading state in solar energy generation among the given options.

Verification / Alternative check:
Examination oriented reference books and standard online practice tests on Indian energy resources frequently mention Rajasthan as the leading solar state. They highlight that Rajasthan crossed significant capacity milestones and houses large solar parks recognised globally. Cross checking multiple such sources gives a consistent picture that Rajasthan is at the top in installed solar capacity, which confirms your selection.

Why Other Options Are Wrong:
Gujarat has been an early leader in solar energy and remains a major contributor, but it is generally ranked behind Rajasthan in total installed solar capacity in recent data.
Haryana has good solar potential and several rooftop initiatives, yet its overall capacity is much smaller compared to Rajasthan.
Uttar Pradesh is expanding its solar portfolio but is still not the leading state at the national level.
Tamil Nadu is strong in both wind and solar, but again, when only solar capacity is considered, Rajasthan typically holds the number one position.

Common Pitfalls:
A common error is to remember older data where Gujarat was highlighted and to assume it still holds the top position. Another pitfall is confusing leadership in overall renewable energy capacity, where different states may dominate because of wind power, with leadership in solar capacity alone. To avoid confusion, remember that Rajasthan, with its large desert areas and multiple mega solar parks, is the key state to associate with maximum solar power generation in current general knowledge questions.

Final Answer:
The state of India that is regarded as leading in solar energy generation is Rajasthan.