The correct answer is option 1: Singapore. Netaji Subhas Chandra Bose announced the formation of the Government of Free India in Singapore in 1943.

Option 2: Shanghai is incorrect. There is no historical record of Netaji Subhas Chandra Bose announcing the formation of the Government of Free India in Shanghai.

Option 3: Berlin is incorrect. Although Netaji Subhas Chandra Bose was in Germany during World War II and had support from the German government, he did not announce the formation of the Government of Free India in Berlin.

Option 4: Mandalay is incorrect. Mandalay, which is located in present-day Myanmar, is not a location associated with the announcement of the Government of Free India by Netaji Subhas Chandra Bose.

In summary, the correct answer is option 1: Singapore, where Netaji Subhas Chandra Bose announced the formation of the Government of Free India in 1943.