[allenciox]

I think that any of a), b), and d) are defensible. If you are confident that you are playing against people that will get their whole stack in with one pair, then it is correct to limp (you want to encourage others to limp, so you have more opportunity to stack them). If you feel that the blinds are imbeciles but the players behind you are tight aggressive (or the type of aggressives that will raise any limps on their button), then you might be good to raise.

In the normative case, where you feel that your postflop play is not a lot greater than those behind you (since they have position), you may want to vary your play, something like 70% fold, 15% limp, and 15% raise, particularly if you are limping small pairs, etc. If all you are limping is small pairs, you are too easy to read.