Which one of the following six letter sequences, when placed in order in the blanks, will correctly complete the pattern _r_r_t_r_r_t?

Introduction / Context:
This question gives a partially completed sequence of letters with fixed letters r and t already in place and six blanks to be filled. One of the provided six letter strings, when inserted sequentially into the blanks, will create a regular and repeating pattern. Problems of this type test the ability to recognise hidden repetition and structure in what initially looks like an irregular sequence.

Given Data / Assumptions:

• The base pattern is _ r _ r _ t _ r _ r _ t.
• There are six blanks to be filled with a chosen six letter sequence, left to right.
• Options for the filler sequence are tpprpp, ttprrp, tpptpp, and ttpprp.
• The resulting completed sequence should show a clear logical or repetitive structure.

Concept / Approach:
We insert each option into the blanks and inspect the full resulting sequence. A good completion will typically show a repeated block of letters or a regular alternation pattern, which is characteristic of well designed alphabet test questions. We avoid random looking results and search for symmetry or repetition.

Step-by-Step Solution:
Step 1: Label the positions. The pattern has 12 positions, with blanks at positions 1, 3, 5, 7, 9, and 11. Step 2: Insert option tpprpp into the blanks. The final sequence becomes trprptrrprpt. Although there is some repetition, it does not form a neat repeated block. Step 3: Insert option ttprrp. The final result is trtrptrrrrpt, which has many r letters grouped together and no simple clearly repeating block. Step 4: Insert option tpptpp. This yields the sequence trprpttrprpt. Step 5: Observe that trprpttrprpt can be split into two identical blocks: trprpt and trprpt. Thus, the sequence is a clean repetition of the six letter block trprpt. Step 6: Insert option ttpprp, which creates trtrptprrrpt. This does not exhibit such a tidy repeated structure.

Verification / Alternative check:
We can clearly see that only option tpptpp results in a sequence that is exactly two copies of the same six letter pattern. Repetition of a block is a strong indication that we have found the intended underlying rule. None of the other options yield a sequence that can be split neatly into equal repeating segments, confirming that tpptpp is the correct choice.

Why Other Options Are Wrong:
The sequences formed by tpprpp, ttprrp, and ttpprp all look somewhat irregular. They contain uneven clusters of letters and cannot be described as a simple repetition of one pattern. Since well structured reasoning questions almost always prefer a clean and elegant rule, these options are considered incorrect completions of the given pattern.

Common Pitfalls:
A common mistake is to choose an option just because it visually resembles parts of the base sequence without checking the full twelve letter result. Candidates may also overlook the idea of block repetition and only look at local similarities. Systematically writing out and then segmenting the resulting sequence helps reveal the true pattern.

Final Answer:
The sequence that correctly completes the pattern is tpptpp, producing trprpttrprpt.