Avoid turning medium pocket pairs into multi-street bluffs on boards that favor the caller's range; check back to realize equity.
Checking is the preferred play here. Our hand has some showdown value but cannot stand a check-raise, and betting doesn't get enough better hands to fold.
Note: Betting 99 here is unnecessary; checking back protects our range and allows us to realize equity on most turns.
Betting the turn is a significant error. The Ace is a scare card that hits the caller's range hard, and our 99 has almost zero equity when called.
Note: Barreling the turn with 99 is over-aggressive; we are turning a hand with marginal showdown value into a pure bluff against a range that contains many Aces.
Folding is the only option. The board is incredibly connected, completing multiple straights (Kx, 89), and our 99 is now just a weak bluff-catcher losing to almost everything UTG bets for value.