This section applies only in Montgomery County. The subdivision regulations may: establish a time period within which the county planning board shall approve or disapprove a preapplication or preliminary plan submission; and provide that an applicant may: waive the time period within which the county planning board shall take action in accordance with item (1) of this subsection; and consent to an extension of the time period. A preapplication or preliminary plan submission that has not been approved or disapproved in accordance with this section is considered approved. If a preapplication or preliminary plan submission is considered to have been approved under this subsection, on demand, the county planning board shall issue a certificate of approval. If the county planning board disapproves a preapplication or preliminary plan submission, the county planning board shall: state the grounds for disapproval in the records of the county planning board; and mail, postage prepaid, a copy of the record stating the grounds for disapproval to all parties of record at their last address.