Which of the following is a most likely consequence of implementing the 'Unified Payments Interface (UPI)'?

1. The Unified Payments Interface (UPI) allows users to link multiple bank accounts in a single mobile application and facilitates instant fund transfers between bank accounts through a mobile device. 2. Option (A) is a most likely consequence. Since UPI enables direct bank-to-bank transfers for online payments (and offline) using a smartphone, it reduces the need for users to first load money into a mobile wallet before making a payment. Therefore, while mobile wallets may still exist for other features, they become less necessary for basic online payments. 3. Option (B) is unlikely. While UPI promotes digital payments, it doesn't automatically mean digital currency will totally replace physical currency, especially within two decades. Physical currency usage persists for various reasons. 4. Option (C) is unlikely. UPI is primarily a domestic payment system. While it improves financial infrastructure, it's unlikely to cause a drastic increase in FDI inflows on its own. 5. Option (D) is possible but not the *most* likely or direct consequence compared to (A). Direct Benefit Transfer (DBT) mechanisms already existed. UPI can be *a* channel for these, but its implementation doesn't inherently make the entire transfer of subsidies system 'very effective' automatically; effectiveness depends on multiple factors.