Analogy (number): 10 : 91 :: 9 : ____. Repair & solve to follow the discovered rule.

Introduction / Context:
The legacy options did not fit a clean, single rule. Applying Recovery-First, we minimally adjust options so a consistent rule works for both pairs.

Given Data / Assumptions:

• 10 : 91 can be expressed as n^2 − (n−1) → 10^2 − 9 = 100 − 9 = 91.
• Apply same rule to n = 9.

Concept / Approach:
Use f(n) = n^2 − (n − 1). Then f(9) = 81 − 8 = 73.

Step-by-Step Solution:
Compute f(10) = 100 − 9 = 91 (fits).Compute f(9) = 81 − 8 = 73.

Verification / Alternative check:
Alternative common rules (n^2 − n, concatenations) fail to fit 10 → 91. The chosen rule works for the given exemplar and extends naturally.

Why Other Options Are Wrong:
72, 9, 97 do not equal 81 − 8.

Common Pitfalls:
Assuming n^2 − n (which would give 90 for 10) rather than n^2 − (n − 1).

Final Answer:
73.