subject is clear to me: a) !! 'cause the ladies are quiet my favorites lol - and if there's no A or K on the flop I'd push all in for sure. Of course there could be a KK or AA waiting for my ladies but please: the chances are not very high....and if: who cares? it's just bad luck!
PS: yesterday I was kicked out a well paid tourney holding the rockets. Some poor fool called my all in with a pair of 4s: and what do you think was the first card on the table??? yes it was a 4! so what?! just bad luck. As I always say: "playing the best poker in the world doesn't mean you can't regularly loose against fools playing bad cards"!!!

Because it's a sit & go, nobody wants to get kicked out quick. You already showed him with your bet that you're having good cards, with a re-raise to all-in you'll show him that you're not kidding and that you're going for it. He may hold a pair or an A or a K or both.
Your opponent has to think about if he loses, then he has only 900.
So a re-raise should scare him, otherwise you're unlucky.

A Fold here would be a good decision because you don't know the player. They probably aren't likely to limp under the gun and then raise huge with nothing especially in a higher stakes sit n go. They probably Have A-A or K-K or A-K. Why would you push when at best you would be in a coin flip and if you do call there are still other ways that you can lose all your money. First if you call and three undercards come your opponent may have hit his set or still has a better overpair. The second would be if an A or a king hits and your opponent pushes with a hand like J-J or 10-10 and there is no way you can call. If you were on the button here it would be a definte call but in this position you can't. You still have planty of chips to play other hans a good tournament player would wait for a better spot to put their life at risk. Plus maybe you'll get in a spot where you can go up against a shorter stack so if you do lose you won't be out.