In the letter series l m _ o _ n m _ l _ n _ _ n m l, which one set of letters, when placed sequentially in the blanks, will complete the pattern correctly?

Introduction / Context:
This question provides a sequence of letters with several blanks: l m _ o _ n m _ l _ n _ _ n m l. We are asked to choose which six letter sequence, when inserted into the blanks in order, completes the pattern. This is a classic letter series completion problem in alphabet tests and evaluates the ability to detect underlying symmetry or repetition in a string of characters.

Given Data / Assumptions:

• Base pattern with blanks: l m _ o _ n m _ l _ n _ _ n m l.
• There are six blanks to be filled in order.
• Options for the six letter sequence: molnon, nolmoo, nomloo, noolmm.
• All letters used are lower case: l, m, n, o.

Concept / Approach:
The approach is to fill the blanks with each candidate sequence and then inspect the resulting string for a logical and aesthetically regular pattern. A strong indicator of correctness is the presence of symmetry, repetition of a central block, or a palindromic structure. The correct completion should reveal a deliberate arrangement rather than an irregular mixture of letters.

Step-by-Step Solution:
Step 1: Remove spaces and consider the base frame lm_onm_l_n__nml, where underscores represent blanks.Step 2: Insert option a) molnon into the blanks to get lmmoonmllnnonnml. This string looks irregular and does not display a clear repeated or symmetric pattern.Step 3: Insert option b) nolmoo to obtain lmnoonmllmnoonml. This string reads the same from left to right and right to left, forming a perfect palindrome.Step 4: Insert option c) nomloo and derive a sequence that is not symmetric and has uneven groupings.Step 5: Insert option d) noolmm and again observe a lack of clean symmetry or simple repetition.Step 6: Among all candidates, lmnoonmllmnoonml from option b shows the most structured arrangement, with the central segment ll acting as a mirror line for the repeating block lmnoonm on both sides.

Verification / Alternative check:
To verify the palindrome property of the string created by option b, we can compare letters from both ends: l matches l, m matches m, n matches n, o matches o, o matches o, n matches n, m matches m, and the central pair ll remains fixed. This symmetrical arrangement strongly suggests that the series was intended to form this mirrored pattern. No other option provides such an elegant and balanced result.

Why Other Options Are Wrong:
The sequences formed by filling options a, c, and d do not show a clear logical organisation and appear more random. There is no central symmetry or simple repeated block pattern. Since reasoning questions usually rely on systematic patterns rather than arbitrary strings, those completions are less plausible and therefore incorrect.

Common Pitfalls:
Some candidates may try to guess the answer by eye without writing out the full string for each option. Others may look for local patterns instead of observing the entire global arrangement. A careful check that includes constructing the complete series and looking for symmetrical properties helps to reliably identify the correct sequence.

Final Answer:
The set of letters that correctly completes the series is nolmoo.