Who among the following can join the National Pension System NPS ........

Economic Affairs Pension and Insurance

Who among the following can join the National Pension System (NPS)?

Resident Indian citizens only

Persons of age from 21 to 55 only

All State Government employees joining the services after the date of notification by the respective State Governments

All Central Government employees including those of Armed Forces joining the services on or after 1St April, 2004

The Central Government had introduced the National Pension System (NPS) with effect from January 1, 2004 (except for armed forces).

Subsequently, various State Governments adopted this architecture and implemented NPS with effect from different dates.
Eligibility – Any citizen of India, whether resident or non-resident, subject to the following conditions.
Individuals who are aged between 18 – 60 years, including NRIs .
After attaining 60 years of age, you will not be permitted to make further contributions to the NPS accounts

Hence option 3rd is correct.