Correct Option: A

Given sequence is
1, 11, 21, 1211, 111221, ........
Now, analyse the terms -
1^st term = 1
2^nd term - It describes the 1^st term term that is has "one" "one" or 11
3^rd term it describes the 2^nd term that it has "two" "one" or 21
4^th term It describes the 3^rd term that it has "one" "2" and "one" "1" or 1211
5^th term It describes the 4^th term that it has "one" "1" "one" "2" and "two" "1" or 111221
Hence the 6 term would be - "Three" "1", "two" "2" and "one" "1" or 312211