To get a clear definition of dropout,______should be taken into account.

A．different kinds of students
B．who is eligible to drop out
C．the definition of dropout developed by CCSSO
D．the changes which can be considered "leaving school"

A．Leaving school to pursue home-based instruction.
B．Shifting to prisons or mental institutions.
C．Leaving school to attend an alternative school.
D．Transferring from a conventional school program into a correctional institution.