Which management entrance exam do I need to qualify in order to pursue MBA?

Yes, you are allowed to opt for more than one. But, all the entrance exams don't work for all the colleges because they have their own internal exam. IT is best if you apply and prepare properly for CAT.

Yes, you can opt for entrance exams like IIFT, CAT, XAT, MAT, CMAT, SNAP, etc. CAT is considered best among all MBA entrances. It's your decision whether to go for CAT or other college specific entrances like XAT/IIFT/SNAP.