Can't tell the difference between permutation and combination In an exam, a student has to answer 6 out of 8 questions. How many ways can she answer the 6 questions if 
a) there are no restrictions?
b) The first 3 questions are compulsory?
c) she must answer at least 3 of the first  4 questions?
I am confused. Why is this question combination? I thought it is supposed to be a permutation. The 6 questions that the student is supposed to answer are specific. For example, each question is unique on its own. That is my understanding, but its wrong ._. Can anyone correct my logic?

I'm not giving actual answers but trying to resolve your confusions.
I wouldn't say the questions are 'specific'.  Each one is either answered or not answered, but the statistically important bit is that they are added together in aggregation for consideration (answer $6$ questions in total).  Thus, for example, answering question number $123678$ is same as $123876$; the order (i.e. permutations) doesn't matter (e.g. answering which ones first).
Hope it helps.
