Which is not true about Regional Rural Banks (RRBs)? i)  RRBs were jointly prompted by Central Govt, State Govt and Sponsor Bank ii)  Regulation of RRBs is done by RBI while responsibility of supervision lies with NABARD iii)  RRBs have been becoming unsustainable due to the mounting losses due to imprudent commercial policy. iv)   The number of RRBs are increasing for achieving greater Financial Inclusion in rural areas