(a) If the board finds that annexation of territory into the district is in the district’s best interest, the board shall, not later than the 90th day after the date the finding is made:
(1) approve the petition filed under Section 1035.152; and
(2) order an election on the question of annexing the territory.
(b) If the board finds that annexation is not in the district’s best interest, the board shall deny the petition filed under Section 1035.152.