Under Section 20(2) of the PFRDA Act, 2013, which of the following is expressly excluded from the basic features of the National Pension System?

Section 20(2)(g) of the PFRDA Act, 2013, uses an emphatic negative formulation: "there shall not be any implicit or explicit assurance of benefits except market based guarantee mechanism to be purchased by the subscriber." This is a deliberate policy choice - the NPS is a defined-contribution, market-linked system, not a defined-benefit scheme promising assured returns from the State. Option (C) inverts this provision by asserting that implicit assurance is a "basic feature," which is the exact opposite of what the statute says. The other options - individual account (cl. (a)), 100% G-Sec option (cl. (d)(a)), 25% partial withdrawal (cl. (b)), and mandatory annuity purchase at exit (cl. (i)) - are all verbatim features enumerated in Section 20(2). The question tests whether the candidate has registered the "no guaranteed benefits" architecture, which is often glossed over in cursory reading. The correct answer is (C).