Which single letter change converts the word "Vertex" into a word meaning "spiral movement"?

Introduction / Context:
Vocabulary-based coding questions often ask for a minimal edit that transforms one valid English word into another with a specific meaning. Here, we need the version that means spiral movement.

Given Data / Assumptions:

• Source word: Vertex.
• Target meaning: spiral movement.
• Only one letter should be changed; other letters stay in their original order.

Concept / Approach:
Recall that the English word for spiral movement is "vortex". We compare "vertex" and "vortex" character by character to locate the minimal change.

Step-by-Step Solution:
1) v e r t e x2) v o r t e x3) Only the second letter differs: e → o. Therefore, the 2nd letter must change.

Verification / Alternative check:
No other single-letter change yields a standard English word meaning spiral movement.

Why Other Options Are Wrong:

• 1st / 4th / Last: Changing these positions does not produce "vortex" nor any correct synonym for spiral motion in this pattern.

Common Pitfalls:
Misremembering spelling ("vortax", "vortix") or attempting multiple changes.

Final Answer:
2nd