Weird Sequences

What is the next term in each sequence?
a) 1, 11, 21, 1211, 111221, ?
b) 10, 11, 12, 13, 14, 20, 22, 101, ? (every term represents the same number)
c) (This is a sequence made by only 2 & 1): 2,2,1,1,2,1,2,2,1, ? ....
Type in only the next term of each sequence, in the order a, b, c, separated by commas.