(a) Within 180 days after the receipt of the County Executive’s comments, recommendations, and fiscal impact analysis as provided in § 21–211 of this subtitle, the district council shall approve, modify, or disapprove the master plan or master plan amendment. (b) On a vote of two–thirds of those present and voting, the district council may extend, by sequential 60–day intervals, the 180–day period for review and action on the master plan or master plan amendment provided in subsection (a) of this section. (c) Failure of the district council to act within the time limits imposed under this section constitutes approval of a master plan or master plan amendment as submitted by the county planning board.