50NL: Difficult spot with KK

PokerStars No-Limit Hold'em, $0.50 BB (8 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

BB ($19.15)
UTG ($52.05)
UTG+1 ($33.15)
MP1 ($101.55)
MP2 ($54.75)
Hero ($89.35)
Button ($29.65)
SB ($45)

Preflop: Hero is CO with K, K.
2 folds, MP1 raises to $1.5, 1 fold, Hero raises to $4.5, 2 folds, BB calls $4, MP1 raises to $14, Hero calls $9.50, BB folds.

Flop: ($32.75) A, A, 4 (2 players)
MP1 bets $15, Hero ???

villain is 30/14/0.84. Ha had won a couple of big pots with good hands to build his stack. My image was tight/aggressive.
He could be betting here with QQ, however, there are a couple of hands with an A (i.e. AA/AK/AQ) that he could have, where I'm behind ...
What would you do on the flop?

you should of shoved PF instead of caling here. i never slowplay KK PF like that.

on flop his range would include more Ax type hands in comparison to QQ type hands