Residents of a PHA designated as troubled pursuant to section 6(j)(2)(A) of the Act (42 U.S.C. 1437d(j)(2)(A)) may petition HUD in writing to take one or more of the actions referred to in section 6(j)(3)(A) of the Act (42 U.S.C. 1437d(j)(3)(A)). HUD will consider any petition from a group of residents totaling at least 20 percent of the PHA's residents, or from an organization or organizations of residents whose membership equals at least 20 percent of the PHA's residents. HUD shall respond to such petitions in a timely manner with a written description of the actions, if any, HUD plans to take and, where applicable, the reasons why such actions differ from the course proposed by the residents. Nothing in this section shall limit HUD's discretion to determine whether a substantial default has occurred or to select the appropriate intervention upon such determination.