Thanks A Lot to both of you!

From your answers I reached to conclude that

I) Subject should be selected from 3 groups at least(200 marks each).

II) Subject can be selected from 6 groups max (all subjects of 100 marks)

III)Subject can also be selected in b/w 3 to 6 groups also if marks of some subjects are 200 and some of them are containing 100 marks.

Is am right?

Thanks again for your help.

Regards,
Shahid Aleem Raja