Correct option is B
Given:
NIGHTMARE
Logic:

So, 2 pairs of letters in the word 'NIGHTMARE'.
Thus, the correct answer is (b).

Suggested Test Series
Suggested Test Series
Find out how many such pairs of letters are there in the given word each of which has as many letters between them in the word as in the English alphabet. HORIZON
In the word ‘MONETARY’, how many pairs of the letters have the same number of letters between them (both forward and backward direction) as in the English alphabet?
In the word "ANALYST", how many pairs of the letters have the same number of letters between them (only in backward direction) as in the English alphabet?