Final answer:
Indeterminate sentencing is a flexible incarceration period followed by potential release based on an individual's rehabilitation, determined by a parole board.
The correct option is a.
Step-by-step explanation:
The type of sentencing scheme where one is sentenced to incarceration for a flexible period and released by a parole board when deemed rehabilitated is known as indeterminate sentencing. In contrast to determinate sentencing, which imposes a fixed sentence length, or mandatory sentencing, which does not allow for judicial discretion in the sentence length, indeterminate sentencing allows for a range of time to be served based on an individual's rehabilitation progress. Unlike concurrent sentencing, which involves serving multiple sentences simultaneously, indeterminate sentencing emphasizes rehabilitation and potential reintegration into society, with parole decisions being made by a parole board that determines when an inmate is ready for release.