In the incomplete letter series _k_m_kl_jk_m, which one set of letters, when placed sequentially in the blanks from left to right, will complete the pattern correctly?

Introduction / Context:
This question involves completing a letter series with a specific pattern. You are given a string of letters with blanks that must be filled using one of the given sequences. Each option is a set of letters that will be inserted into the blanks in order. The task is to find the option that produces a smooth and consistent pattern after substitution.

Given Data / Assumptions:
Base pattern: _k_m_kl_jk_m.
There are five blanks in total.
Each option provides a sequence of five letters that will be placed in the blanks from left to right.
We must choose the option that produces a meaningful and regular letter pattern.

Concept / Approach:
The usual approach is to mentally or on paper insert each candidate sequence into the blanks and then observe the resulting full string. We look for repeating groups or a clear simple pattern. In many such questions, the completed series becomes a repeated short block of letters such as jklm. If we recognise a clean repetition, that is usually the correct completion.

Step-by-Step Solution:
Step 1: The pattern has blanks at positions 1, 3, 5, 8, and 11 in the string _k_m_kl_jk_m. Step 2: Insert option b, which is jljml, into the blanks. Step 3: Fill in the blanks one by one. Position 1 becomes j, position 3 becomes l, position 5 becomes j, position 8 becomes m, and position 11 becomes l. Step 4: The completed sequence is j k l m j k l m j k l m when spaces are added for clarity, which reads as jklm repeated three times. Step 5: This creates a neat repetition of the four letter sequence jklm, which is a highly regular and expected pattern in alphabet test questions.

Verification / Alternative check:
If we try other options, the resulting full strings do not form such a clean repeating pattern. For example, option a or c produce irregular sequences like jklmjklljkmm or jklmlklmjkjm, which lack a simple repeated block structure. The elegance and symmetry of jklmjklmjklm strongly indicate that option b is the intended solution.

Why Other Options Are Wrong:
jljlm: Produces a pattern with inconsistent internal structure and does not result in a smooth repetition.

jllmj and jllmm: These combinations create jumbled letter sequences where the underlying block of letters changes shape across repetitions.

jmljl: This also fails to generate any standard or easy to recognise repeated unit.

Common Pitfalls:
Many learners attempt to interpret the pattern directly without actually substituting each candidate. This can lead to incorrect guesses. The safer strategy is to explicitly fill in the blanks for each option and write down the full sequence. The correct pattern is usually the one that is the simplest and most regular after substitution.

Final Answer:
The option that completes the pattern is jljml, which turns the series into jklmjklmjklm.