The correct answer is option 4, Yangon. To determine which city is geographically nearest to Port Blair, it is necessary to consider the distances between all the given options.
Option 1, Kolkata, is the capital city of the Indian state of West Bengal. Although it is geographically close to Port Blair, it is not the closest city.
Option 2, Kuala Lumpur, is the capital city of Malaysia. It is located in a different country and is geographically far from Port Blair. Therefore, it is not the nearest city.
Option 3, Singapore, is a sovereign city-state and island country located in Southeast Asia. While it is relatively close to Port Blair, it is not the nearest city.
Option 4, Yangon, is the largest city and former capital of Myanmar (formerly known as Burma). Myanmar is neighboring country to India and shares a border with it. Therefore, Yangon is the nearest city geographically to Port Blair.
In conclusion, among the given options, Yangon is the city that is geographically nearest to Port Blair.