To speak or not to speak, that is the question

[Feroc]

[ QUOTE ]
After the turn card is dealt, Player A bets $15. Player B moves all-in for $25. Player C calls. The dealer turns back to A, who immediately pushes all-in for around $90. As the dealer turns to C for his action, I speak up and point out that A does not have the option to re-raise there.

[/ QUOTE ]

Sorry to ask, but why is it no option for A to re-raise? I never played in a casino, as I couldn't afford it. So I only play online. But when I see it right, A bets, B raises AI, C calls the raise... so why can A only call or fold?!