I was referring to the elder scrolls iv. What's c&c?
Choices and Consequences
It means that every choice you make should have a real consequence or effect on the game.
Many choices don't really have consequences in a lot of games - for instance, if you have a choice of two paths to take, and each path has equal challenges and leads to the same destination, choosing which path to take was a 'fake' choice. It looked like it made a difference, but no matter which path you decided on, the outcome is the same.
If, on the other hand, you have the choice of two paths to take, and each leads to a different destination, that would give a real consequence to your choice, especially if by taking one path you could never go back and take the other path.
In New Vegas, this would translate to a choice of which faction to side with. It shouldn't be an easy choice. A good indicator of a fake choice or false choice or one lacking consequences is that they will almost always be 'easy' or 'quick' choices. If you choose one side, say the NCR, and take missions from them blowing up Legion assets, you shouldn't be able to waltz in a Legion camp and get missions from them.
If you are familiar with FO3, the Tenpenny Tower quest is probably the best example of choice and consequences played out. You must think carefully about who to side with, and your actions can have long reaching effects, some of them not immediately apparent until much later.
Going back to the Oblivion examples, where the different guilds were concerned, there was no C&C. Joining a guild was an easy choice, because that choice didn't lock you out of anything else or have negative effects to balance out the positive effects. If the opportunity presented itself to join a guild, there was no true choice present, because the only smart thing to do was
join the guild. Any choice with an optimal option for all playthroughs is NOT a real choice. The game may as well make it for you, because the choice bears no consequence.
I hope I helped you understand it more. I like Oblivion, but the more C&C a game has the better it is. Also the more C&C the more fun replays are. Hopefully New Vegas will have C&C in spades.