The letters in the series are placed such that the number of letters skipped between adjacent letters increases by a constant value. Which of the following series observes this rule?

How many such pairs of letters are there in the word $CHILDREN$ each of which has as many letters between them in the word as there are between them in the English alphabet?

$A$ group of letters is given which are numbered $1, 2, 3, 4, 5$ and $6$. Below are given four alternatives containing combinations of these numbers. Select the combination of numbers so that the letters arranged accordingly form a meaningful word.
$K, A, T, C, E, L$
$1, 2, 3, 4, 5, 6$

Which one word can be formed from the following letters?
$a, a, b, c, i, l, l, n, o, o, o, r, t$

Arrange the given words in alphabetical order and choose the one that comes in the second place:

$A$ group of letters is given which are numbered $1, 2, 3, 4, 5$ and $6$. Below are given four alternatives containing combinations of these numbers. Select the combination of numbers so that the letters arranged accordingly form a meaningful word.
$E, L, G, N, I, M$
$1, 2, 3, 4, 5, 6$