Which of the following are key directives of the Sarbanes$-$Oxley Act to enforce the independence of auditors? $($Check all that apply.$)$

It mandates public accounting firms to provide audit services to any company irrespective of any conditions.

It mandates junior auditors to rotate off an account every seven years and senior auditors every five years.

It forbids specific "nonaudit" services of public accounting firms as breaches of auditor independence.

It allows public accounting firms' to employ senior officers of their clients before providing audit services.