The world's largest floating solar farm was launched in which of the following countries?

Introduction / Context:
Floating solar farms are large arrays of solar panels installed on the surface of water bodies such as lakes, reservoirs, and flooded mines. This question tests knowledge of global renewable energy developments, specifically which country has been leading in deploying the world's largest floating solar farm. Understanding such projects is important for general awareness about sustainability, climate change mitigation, and advances in solar technology.

Given Data / Assumptions:

• The question asks about the country where the world's largest floating solar farm was launched.
• Options provided are Japan, China, Russia, and France.
• We consider widely reported international projects that have held the record for largest floating solar farm.
• The focus is on a large-scale, grid-connected floating solar installation.

Concept / Approach:
Floating solar farms are assessed by their installed capacity (in megawatts) and total surface area. Over the last decade, several countries have built floating solar plants, but China has been particularly aggressive in scaling up such projects on former coal mines and reservoirs. To answer the question, we match the country most widely reported as hosting the world's largest floating solar farm at the time these records were noted.

Step-by-Step Solution:
Step 1: Recall that both Japan and China pioneered early floating solar installations, but China later built significantly larger projects. Step 2: Identify the famous large floating solar plants in Huainan (Anhui province) and other Chinese locations, which have often been described as the world's largest floating solar farms. Step 3: Check that Russia and France have notable energy projects but are not commonly cited as having the world's largest floating solar farm. Step 4: Therefore, among the given options, China is the correct country associated with the world's largest floating solar farm.

Verification / Alternative check:
Many international energy and news reports highlight a large floating solar farm built on a flooded former coal mine in Huainan, China, and other large Chinese floating projects that have set world records for capacity and size. Japan did build early floating solar plants, but their capacity is clearly lower than the biggest Chinese installations. Russia and France are not known for holding this particular world record. This confirms that China best fits the description among the options.

Why Other Options Are Wrong:
Japan: Japan developed some pioneering floating solar plants, but their capacity is lower than the largest Chinese farms, so Japan does not currently hold the record.
Russia: Russia is rich in energy resources, mainly fossil fuels, but it is not known as the host of the world's largest floating solar farm.
France: France invests significantly in nuclear and some renewable energy, yet it is not associated with the largest floating solar project worldwide.

Common Pitfalls:
A common mistake is to associate Japan with the answer simply because it was an early adopter of floating solar technology and often appears in earlier GK materials. Another confusion is assuming that any technologically advanced country like France must host the largest project, without checking up-to-date records. Students should remember that China frequently leads in the world's biggest renewable energy installations, including solar power capacity.

Final Answer:
Thus, the world's largest floating solar farm was launched in China.