Option 1 -> May - GST was not launched in this month.
Option 2 -> June - Final preparations were underway, but GST had not yet been implemented.
Option 3 -> July - GST became operational on July 1, 2017.
Option 4 -> August - GST was already operational by this month.
Hence, Option 3: July -> The Goods and Services Tax (GST) was officially launched at midnight on July 1, 2017, in India. This historic tax reform replaced multiple indirect taxes like VAT, service tax, excise duty, and others with a unified taxation system. The launch event took place in the Central Hall of Parliament with the President and Prime Minister in attendance, marking it as one of the most significant economic reforms in India's post-independence history. -> correct