C. is 0 in how many ways can one write the elements 1, 2, 3, 4 in a sequence x, x2, x3, x4 with i v ? a. 9 c. 11 b. 10 d. 12

See the condition here State that i=\ i. That means that one element used would go on missing in the next. So leaving one in 1st we get 3 & then in 2nd we use the one left and 2 o...

Correct Answer is option (A).