According to the Westminster Confession, what is the Biblical basis for the belief that the guilt of Adam and Eve was imputed to all mankind?

As a recent answer observes, the Westminster Confession of Faith explains: >Our first parents, being seduced by the subtilty and temptation of Satan, sinned, in eating the forbidden fruit. This their sin, God was pleased, according to His wise and holy counsel, to permit, having purposed to order it to His own glory. > >II. By this sin they fell from their original righteousness and communion with God, and so became dead in sin, and wholly defiled in all the parts and faculties of soul and body. > >III. They being the root of all mankind, the guilt of this sin was imputed; and the same death in sin, and corrupted nature, conveyed to all their posterity descending from them by ordinary generation.* What Biblical basis does the Westminster Confession imply or state supports the statement, "the guilt of this sin was imputed"? If the Confession itself makes no such support, are there authoritative commentaries on the Confession (and only on the Confession) that provide such basis, and, if so, what is claimed? Please don't answer the more general question, "What is the Biblical basis for the belief that the guilt of Adam and Eve was imputed to all mankind?" That is not what is being asked here. (Thank you.) * VI.1-3