Opponent is absolutely unknown.

PokerStars No-Limit Hold'em, $0.25 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($15.20)
SB ($22.85)
BB ($31.65)
UTG ($25.65)
Hero ($25)

Preflop: Hero is MP with 7, 8.
1 fold, Hero raises to $1, 1 fold, SB calls $0.90, 1 fold.

Flop: ($2.25) 4, Q, A (2 players)
SB bets $0.5, Hero raises to $2, SB calls $1.50.

Turn: ($6.25) Q (2 players)
SB bets $0.5, Hero raises to $4.5, SB raises to $8.5