Had just sat down at this table, no read on anyone.

Ultimate Bet
No Limit Holdem Ring game
Blinds: $0.25./$0.50.
5 players
Converter

Stack sizes:
UTG: $120.50
CO: $31.95
Button: $37.65
Hero: $27.90
BB: $18.25

Pre-flop: (5 players) Hero is SB with
UTG calls, 2 folds, Hero calls, BB checks.

Flop: ($1.5, 3 players)
Hero bets $1, BB folds, UTG calls.

Turn: ($3.5, 2 players)
Hero bets $2, UTG calls.

River: ($7.5, 2 players)
Hero checks, UTG bets $4.5,
Hero ?

Basically, call or raise?