Choose the 4-letter fill that yields a consistent st–tt–ts tapestry: — s t t — t t — t t s —

Introduction / Context:We are asked to restore a pattern built from t and s. The shown fragments suggest alternating clusters “st”, “tt”, “ts”.

Given Data / Assumptions:Four letters fill four gaps in order.

Concept / Approach:Test each candidate and confirm that every two-letter window cycles through the indicated clusters without contradiction.

Step-by-Step Solution:

Verification / Alternative check:Write out the completed string and check successive bigrams.

Why Other Options Are Wrong:They create doubled bigrams where the pattern calls for alternation.

Common Pitfalls:Reading the blanks out of order.

Final Answer:tsts