Analogy — choose the part-to-whole relation that matches Arc : Circle.

Introduction / Context:
“Arc : Circle” shows a strict part–whole geometric relation: an arc is a portion of a circle. We must select a pair that preserves this geometric subset relation with the same order (part → whole).

Given Data / Assumptions:

• An arc is part of a circle.
• We need a smaller geometric entity that is part of a larger one.
• Order must remain part first, whole second.

Concept / Approach:
A segment is part of a line (a line segment). This is the closest parallel in elementary geometry: both pairs describe a portion of a fundamental geometric object.

Step-by-Step Solution:

Verification / Alternative check:
Define terms: a line segment is any finite part of a line; an arc is any connected part of a circle. The structural analogy matches perfectly.

Why Other Options Are Wrong:

• Number : Count — abstract relation, not part–whole geometry.
• Fraction : Percentage — equivalent representations, not part–whole.
• Pie : Slice — reversed (whole : part), not part first.

Common Pitfalls:
Choosing conceptually related terms but missing the explicit part-first order. Always align both the relation and its direction with the stem pair.

Final Answer:
Segment : Line