Analogy — Choose the pair that preserves the same relationship: Rectangle : Pentagon :: ____

Introduction / Context:
This is a shape–sides progression analogy. A rectangle (4 sides) becomes a pentagon (5 sides) by increasing the side count by one. We must pick the option that mirrors this specific “+1 side” transition.

Given Data / Assumptions:

• Rectangle has 4 sides; pentagon has 5 sides.
• The rule is “polygon with n sides → polygon with n+1 sides”.

Concept / Approach:
Map the same operation to a different starting polygon. A triangle has 3 sides; add one side to get a quadrilateral (rectangle is a special quadrilateral).

Step-by-Step Solution:

Verification / Alternative check:
No other option presents a clean “adjacent polygon by sides” relation.

Why Other Options Are Wrong:

• Diagonal : Perimeter and Side : Angle — not polygons nor a “+1 sides” progression.
• Circle : Square — circle is not a polygon and does not fit the sides rule.

Common Pitfalls:
Confusing any shape pairing with the specific numeric progression.

Final Answer:
Triangle : Rectangle