Explanation:

Third option is correct.

The Goods and Services Tax was an initiative undertaken by the Modi government to bring most commodities sold in India under one major tax bracket. This would result in lesser calculations and more ease in payment of the tax.
Before the GST, VAT was the primary form of tax that was levied on the mobile phone, and as the VAT rates varied from state to state, it was difficult to fix a standard price for the phone. Under GST, the rate of tax is the same across the length and breadth of India, and hence some much-needed uniformity has seeped into the Indian market.