Understanding the Letter Series Completion

The question asks us to identify the correct sequence of letters from the options that, when placed in the blanks, will complete the given letter series and follow a specific pattern.

The series provided is:

I _ F I _ N D _ F _ I N N _ I F F _ N _ D

Counting the blanks, we find there are 8 empty spaces that need to be filled.

Analyzing the Provided Option

We are given options with sequences of letters. Let's consider the sequence from the correct option, which is F N I F D I N.

This sequence contains 7 letters, while the series has 8 blanks. Following the instruction to place these letters sequentially in the blanks from left to right, we will place the first 7 letters into the first 7 blanks.

• The 1st blank will be filled with 'F'.
• The 2nd blank will be filled with 'N'.
• The 3rd blank will be filled with 'I'.
• The 4th blank will be filled with 'F'.
• The 5th blank will be filled with 'D'.
• The 6th blank will be filled with 'I'.
• The 7th blank will be filled with 'N'.

After placing these letters into the first 7 blanks, the series becomes:

I F F I N N D I F F I N N D I F F I N N D _ D

Identifying the Pattern in the Completed Series

Let's look closely at the series with the first 7 blanks filled:

I F F I N N D I F F I N N D I F F I N N D _ D

Upon examining this sequence, we can observe a repeating block of letters:

• The first 7 letters form the block I F F I N N D.
• The next 7 letters (starting from the 8th position) also form the block I F F I N N D.
• The following letters start with I F F I N N D followed by the 8th blank and the letter D at the end of the original series.

The letters placed in the first 7 blanks (F, N, I, F, D, I, N) are precisely the letters required to complete the first two repetitions and begin the third repetition of the 7-letter pattern I F F I N N D across the blank positions in the original series structure.

Specifically, the blanks correspond to positions where the letters from the repeating unit I F F I N N D would fall:

• 1st blank (Pos 2): F (from IFFINND)
• 2nd blank (Pos 5): N (from IFFINND)
• 3rd blank (Pos 8): I (from IFFINNDI - start of next block)
• 4th blank (Pos 10): F (from IFFINND - start of next block)
• 5th blank (Pos 14): D (from IFFINND - end of block)
• 6th blank (Pos 18): I (from IFFINNDI - start of next block)
• 7th blank (Pos 20): N (from IFFINND - start of next block)
• 8th blank (Pos 23): _ (should be D to complete the pattern)

The sequence F N I F D I N corresponds to the letters that should fill the first seven blanks to reveal this underlying structure based on the pattern I F F I N N D.

Conclusion

Placing the sequence F N I F D I N into the first seven blanks of the series helps in identifying the repeating pattern I F F I N N D. The letters in this sequence correctly fill the positions required by this pattern within the first seven blanks.