Refer to the excerpt below
"We might feel the pride in the reflection, that our young country...was the first to adopt with any efficacy, the penitentiary system of prison discipline, and the first to attempt to prevent the commission of crimes, by seeking out the youthful and unprotected, who were in the way of temptation, and by religious and moral instruction, by imparting to them useful knowledge, and by giving them industrious and orderly habits, rescuing them from vice, and rendering them valuable members of society...To confine these youthful criminals...where no, or scarcely any, distinction can be made between the young and the old, or between the more or less vicious, where little can be learned but the ways of the wicked, and Form whence they must be sent to encounter new wants, new temptation, and to commit new crimes, is to pursue a course, as little reconcilable with justice as humanity: yet, till the House of Refuge was established there was no alternative."
Society for the Reformation of Juvenile Delinquents in the City of New York, Fourth Annual Report, 1829
The above account best reflects what growing reform sentiment during the period 1820 to 1848?
A) Commitment to egalitarianism
B) Acceptance of transcendental philosophy
C) Commitment to the philosophy of predestination
D) Belief in the perfectibility of man

This is because, the society has always believed that , prison was made for the reformation and jailing of people that committed crimes but the country USA goes ahead to shpw that, the young people can be prevented from committing crime by engaging them early and protecting those that might be exposed to crime.

Doing this would help to ensure that, no one would found his or her way to the prison thereby showcasing the belief in the perfectibility of man.