under raising rule interesting question

[john kane]

hi, last night at our society tournament we had this debate:
3 players see the flop:
chip stakes: player A 33,000ish, player B 35,000ish, player C 10,000.
flop comes and:

player A bets 3,000
player B raises 5,000 (to make it 8,000)
player C goes all in for a total of 10,000 (ie underraising it by 2,000)

now, player A, faced with a raise and a under-rereraise still had about 30,000.

can player A reraise?????

some of us thought no, as he was faced with an underraise. however some of us thought yes, as he shoud be able to reraise player B raise of 5000.

those who thought yes, suggested that otherwise player B could manipulate his raise size to ensure if player C were to go all in then player A could or could not reraise (depending on what player B would aim for) i.e if player B wanted player A to reraise, then he would only raise 3000 (to 6000 in total), so if player C were to go all in (a reraise of then 4000), then player A could reraise.

just a interesting one i thought, what are your thoughts, can player A reraise???