C. checking will possibly draw him into betting further.

my choice is E...for EZ check...lol.

The big blind thinks you are stealing due to your position and the limpers. Hes probbaly chancing it but the fact that he checks after the flop says AX with a big diamond
The chances of the BB hitting the flush on the flop are 117.8:1. So its unlikley.
Pretty good chance that hes betting with and ace or king, big pair or high runners and one of those may well be a diamond in which case he has 35% of hitting in the next 2 cards.
You are currently ahead with nut set and have, at worst, 31% of securing the FH, even if he has the flush you still can afford to safely bet or call almost 4 X the big blind. If you make a substantial raise you might take the pot down, but if not you get the most info back. If the bb calls then hes probably chasing or has AQ or 2 pair if he pushes hes on the flush. Depending on his stack if you are getting 3-1 approx pot odds you can still call. If you make a small raise your inviting the chaser to hit, if you push you're a fud. Which is most likely what i'd do under those circumstances. If you make a substantial raise and lose, 50% of the flop say, you can seek solace in the fact that you played well and the other guy made a noob call

C. Check..:)

AAAAAAAAAAAAAAAA no gpokr suck out for me

if you push all in and they do have a flush your busted, you have no info

go all in

RAISE BIG ITS GPOKER

D...a small raise won't scare him away and you move on to the turn where you get a chance to see what your odds really are

*