Option 1 -> November 2016 is when the demonetization was announced on November 8, 2016.
Option 2 -> December 2016 was after the demonetization had already been implemented.
Option 3 -> March 2016 was several months before the demonetization.
Option 4 -> April 2017 was months after the demonetization.
Hence, November 2016 -> The Government of India announced the demonetization of ₹500 and ₹1000 banknotes on November 8, 2016, effective from midnight. This was done to curb black money, counterfeit currency, and corruption. -> correct