Assistance may be made under this subchapter only if the grantee certifies that it is following—
(1)
a current housing affordability strategy which has been approved by the Secretary in accordance with section
12705 of this title, or
(2)
a comprehensive homeless assistance plan which was approved by the Secretary during the 180-day period beginning on November 28, 1990, or during such longer period as may be prescribed by the Secretary in any case for good cause.