Arrange the “Bi…” words in dictionary order (A→Z). Words: (i) Billian, (ii) Bifurcate, (iii) Bilateral, (iv) Bilirubin. Choose the strict alphabetical sequence.

Introduction / Context:
All words share the “bi…” prefix. We must compare the subsequent letters methodically to avoid swapping near neighbors, especially among the “bila…” and “bili…” cluster.

Given Data / Assumptions:

• Words: Bifurcate, Bilateral, Billian, Bilirubin.
• Compare case-insensitively and ignore meanings.

Concept / Approach:
First, “bif…” precedes any “bil…”. Among the “bil…” group, compare letter by letter: “bila…” vs “billi…” vs “bili r…”. “bila…” (with “a”) precedes “bili…”. Between “billian” and “bilirubin”, “billian” has “…billi a n” while “bilirubin” is “…bili r…”, and since “a” < “r”, “billian” precedes “bilirubin”.

Step-by-Step Solution:
Order: (ii) Bifurcate → (iii) Bilateral → (i) Billian → (iv) Bilirubin.

Verification / Alternative check:
Check each adjacent pair using character-by-character comparison to confirm no reversals.

Why Other Options Are Wrong:
They invert the internal order within the “bil…” cluster (often swapping Billian and Bilirubin) or place a “bil…” word ahead of “bif…”.

Common Pitfalls:

• Sorting by familiarity (e.g., Bilirubin is common in medicine) rather than letters.

Final Answer:
(ii), (iii), (i), (iv).