Q 72

A fighter masters both Robilar's Gambit (Player's Handbook II) and Grappling Block (Oriental Adventure).

A) While using Robilar's Gambit, he can choose to make an attack of opportunity at any attacker that miss. However, on the first armed attack that hits, can he choose to use his once-a-round Grappling Block attempt instead?

B) Whatever the case, he cannot make both the Robilar's Gambit-granted AoO and the Grappling Block on the same swing, based on the rule that the same action cannot provoke two attacks of opportunity, right?