On which of the following days is National Unity Day celebrated?

In India, on 31 October every year, the birthday of Sardar Vallabhbhai Patel is celebrated as National Unity Day. The year 2014 was celebrated for the first time with the aim of paying tribute to the 'Iron Man of India'. In the year 2018, the Government of India unveiled the Statue of Unity in Gujarat in honor of Sardar Patel. It is the highest statue in the world. Sardar Patel was born on 31 October 1875 in Nadiad Gujarat. He was the first Home Minister and Deputy Prime Minister of India.