The correct answer is option 2. The main reason for the Prime Minister of India to make a three-day visit to Russia in May 2005 was to attend the commemorations of the 60th anniversary of the victory of the Allied Forces over Germany in World War II.

Option 1, which suggests that the visit was to persuade Russia to ensure a permanent seat in the UN Security Council with veto power, is not correct. While India has long sought a permanent seat in the UN Security Council, this was not the main reason for the Prime Minister`s visit to Russia in 2005.

Option 3, which suggests that the visit was to develop a strategic defense partnership between China, India, and Russia, is also not correct. While India has indeed sought to strengthen its defense partnerships with various countries, there is no mention of this being the main reason for the Prime Minister`s visit to Russia in 2005.

Option 4, which suggests that the visit was to promote trade between Russia, other CIS members, and India, is not mentioned as the main reason for the visit. While promoting trade and economic relations may have been a part of the Prime Minister`s agenda during the visit, it is not specified as the main reason.

In summary, the main