Foreign Direct Investment (FDI) involves establishing a lasting interest and control over an enterprise resident in an economy other than that of the investor. Foreign Currency Convertible Bonds (FCCBs) and Global Depository Receipts (GDRs) are instruments that can be converted into equity, thus potentially leading to foreign direct investment. Foreign Institutional Investment (FII), while a significant capital inflow, is typically considered portfolio investment unless it meets specific criteria for control or significant influence, which is implied by 'certain conditions' in option 2. Non-Resident External (NRE) deposits are generally considered debt instruments or savings, not direct investment in productive assets of an enterprise.