Which of the Following Statements Is NOT One of the Reasons

Which of the following statements is NOT one of the reasons why,in modern industrial societies,it is unclear when adolescence ends?

A) Complex industrial societies require a long period of education,which postpones adulthood beyond the attainment of physical maturity.
B) Most of these societies have no definitive markers to establish adulthood.
C) Puberty in these societies is beginning much later than it used to,because young people are less active and less physically fit.
D) Vocational apprenticeships are rare or absent in these societies.