**India's Longest International Boundary**

The correct answer is option D - Bangladesh. India shares its longest international boundary with Bangladesh. Let's delve into the details below.

**Geographical Background:**
India is a South Asian country with a diverse landscape and borders several countries. Its geographical location in the Indian subcontinent places it in close proximity to its neighboring nations. The country shares its borders with Pakistan, China, Nepal, Bhutan, Bangladesh, and Myanmar.

**Length of the Boundary:**
The India-Bangladesh border is the longest international boundary that India shares with any country. It stretches approximately 4,096 kilometers (2,545 miles) in length. This boundary separates the Indian states of West Bengal, Tripura, Assam, Meghalaya, and Mizoram from the neighboring country of Bangladesh.

**Historical Significance:**
The India-Bangladesh border has a significant historical background. It was established after the partition of India in 1947, when the British Indian Empire was divided into two separate nations - India and Pakistan. East Pakistan, which later became Bangladesh, was initially a part of Pakistan. However, due to political and cultural differences, East Pakistan fought for independence from West Pakistan, leading to the Bangladesh Liberation War in 1971.

**Border Disputes and Agreements:**
Over the years, India and Bangladesh have resolved several border disputes through diplomatic negotiations and agreements. The most notable agreement is the Land Boundary Agreement (LBA) signed in 1974. The LBA aimed to resolve the complex border issues, including the demarcation of the boundary and exchange of enclaves.

In 2015, a historic agreement known as the "Land Boundary Agreement 2015" was signed between the two nations. This agreement resolved the long-standing border disputes, enabling the exchange of 162 enclaves between India and Bangladesh.

**Importance and Relations:**
The India-Bangladesh border holds immense significance due to various factors. The border facilitates trade, cultural exchanges, and people-to-people contact between the two nations. Several border checkpoints and land ports have been established to enhance trade and connectivity.

Moreover, India and Bangladesh share strong bilateral relations, focusing on cooperation in areas such as security, trade, energy, connectivity, and development. The two countries have collaborated on various infrastructural projects, such as the construction of bridges, roads, and railways, to enhance connectivity and boost economic ties.

In conclusion, India shares its longest international boundary with Bangladesh, spanning approximately 4,096 kilometers. This border holds historical significance and has witnessed border disputes and subsequent agreements. The India-Bangladesh border plays a vital role in promoting trade, cultural exchanges, and bilateral relations between the two nations.

Yes border length of china with India is 3488km and bangladesh is 4096km