Which of the following statements is NOT true about the Agnipath Scheme?

a) The scheme will allow youths to serve in the armed forces for four years.
b) Enrolment will be based on a "regiment system". 
c) Eligible age will be in the range from 17.5 to 21 years. 
d) The government has raised the upper limit from 21 to 23 years for the year 2022.