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

The word given is SERVITUDE. Lets start with 1st letter and then proceed in sequential order to figure out the required pairs. SE does not fulfill our requirement as does not have any letter between them, whereas in english alphabets they have 13 letters between them. Moving on to SR, it is again not a possible pair since it does not have any letter between them in english alphabets whereas here we have 1. So on proceeding in a similar manner, we can find that following pairs fulfill our requirement
SV VT IE TU DE, so since we have wound 5 pairs, the answer is option 5.