Grandma Jones bought 15 identical chocolate bars for her six grandchildren (named A,B,C,D,E and F).

How many possible ways to divide those bars are there for each of the following exclusive cases:

a) Each of the grandchildren gets a distinct number of bars
b) Only two of the grandchildren get the same number of bars
c) Each of the grandchildren gets at least 1 chocolate bar
d) No restrictions
e) A gets more than B, no other restrictions