In the following letter series, blanks represent missing letters: _tu_rt_s__usrtu_. Choose the option that supplies the missing letters in the correct order.

Introduction / Context:

This question features an incomplete letter series with specific blanks to be filled. The correct option must supply letters that, when placed into the blanks in order, create a coherent and preferably repetitive pattern. Such questions test visual pattern recognition and the ability to reconstruct underlying repeating sequences from partial information.

Given Data / Assumptions:

• The series is written as _tu_rt_s__usrtu_.
• There are six blanks, each to be filled by one letter.
• Each answer option gives six letters that must be inserted into the blanks from left to right.
• The resulting full string should follow a neat repeating pattern if the option is correct.

Concept / Approach:

The approach is to substitute each option into the blanks and then inspect the resulting string. The correct choice is usually the one that turns the entire sequence into a clean repetition of a small letter block. In this question, the letters t, u, s, r appear frequently, hinting at a repeated block such as rtus or usrt. Our goal is to find which option, when substituted, produces a regular repetition of such a block without inconsistencies.

Step-by-Step Solution:

Step 1: Represent the pattern with blanks as _ t u _ r t _ s _ _ u s r t u _ in a continuous form. Step 2: Take option rsurts, which has six letters: r, s, u, r, t, s. Step 3: Substitute these into the blanks in order. The final string becomes r t u s r t u s r t u s r t u s, which can be grouped as rtus repeated four times. Step 4: The block rtus is clearly and exactly repeated without interruption, which is a very strong indication of a correct option. Step 5: This repetition demonstrates that rsurts provides the missing letters in precisely the right order.

Verification / Alternative check:

To validate, we can test another option to see that it fails to produce such neat repetition. For example, substituting rsutrr will not yield a pure repetition of rtus or any other simple block, and irregular combinations of letters will appear. The same happens with rsurtr and rtusru, none of which simplifies into a clean repeated pattern across the entire string. Only rsurts transforms the series into rtusrtusrtusrtus, an exact repetition of a four letter block, confirming that this option is the correct choice.

Why Other Options Are Wrong:

Option rsutrr introduces extra r letters that break the uniform rhythm of rtus. Option rsurtr results in mixed segments that do not align as pure repetitions of a single block. Option rtusru changes the relative order of letters and fails to construct a consistent basic unit that can be repeated. Option rrtuss also fails to generate any obvious repeating structure. In all of these options, the finished sequences contain irregular segments that do not match standard exam expectations of a well structured series.

Common Pitfalls:

Some candidates try to reason only locally, checking a few letters before and after each blank, but do not inspect the global string after substitution. Others ignore the possibility of a repeating block and instead attempt to impose complex rules on a short segment. A systematic approach that tests each option and then looks for an overall repeating pattern is less error prone and much more efficient in such questions.

Final Answer:

The sequence of letters that correctly completes the series as a repetition of rtus is rsurts.