In the following list of numerals, how many 2's are followed by 1's but not preceded by 4 ?
4 2 1 2 1 4 2 1 1 2 4 4 4 1 2 2 1 2 1 2 1 4 4 2 1 4 2 1 2 1 2 4 1 4 2 1 2 4 1 4 6
1) 2
2) 3
3) 4
4) 5
5) None of these

Explanation

3, 4