rules question- checkraising bet+less than minraise

[2ndGoat]

Player A checks.
Player B bets $100.
Player C raises all-in to $125.

I believe player A can raise here, since the bet by player B re-opened the action for him even though Player C's raise did not.

But what is his minimum raise? I would think to $225 but it's just a shot in the dark.

2nd

[2ndGoat]

Found it.

From Bob Ciaffone's "Robert's Rules of poker":

5. “Completing the bet” is a limit poker wager type only, not allowed at big-bet poker. For example, if a player bets $100 and the next player goes all-in for $140, a player wishing to raise must make the total bet at least $240 (unless going all-in).

So in my case, $225 it is. I generally defer to Mr. Ciaffone on such matters.