Permutations and combinations

I have 2 questions

1) A question paper contains 6 questions,each havinbg an alternative.The number of ways and examinee can answer one

or more questions is

a)720  b)728  c)729  d)None of these

2)The number of ways in which 12 students can be equally divided into 3 groups is

a)5775  b)7575  c)7755 d)none of these

Thanks in advance