Four-digit numbers are to be formed using the digits 1, 2, 3 and 4; and none of these four digits are repeated in any manner. Further,
2 and 3 are not to immediately follow each other
1 is not to be immediately followed by 3
4 is not to appear at the last place
1 is not to appear at the first place
How many different numbers can be formed?
(a) 6
(b) 8
(c) 9
(d) of the above
