If the word PROJECT is coded as KILQVXG using a fixed letter-substitution rule (each letter is replaced by its opposite letter in the alphabet, such as A↔Z, B↔Y, C↔X, etc.), then how will the word EGO be coded using the same opposite-letter (Atbash) rule?

Introduction / Context:
This question tests a substitution cipher where each letter is replaced by its opposite letter in the alphabet. This is commonly known as the Atbash pattern: A↔Z, B↔Y, C↔X, ..., M↔N. The example PROJECT → KILQVXG matches this opposite-letter substitution.

Given Data / Assumptions:

• PROJECT is coded as KILQVXG.
• Rule: each letter maps to its opposite in the alphabet (Atbash).
• Opposite pairs: A-Z, B-Y, C-X, D-W, E-V, F-U, G-T, H-S, I-R, J-Q, K-P, L-O, M-N.
• Find the code for EGO.

Concept / Approach:
Identify that P→K, R→I, O→L, etc., corresponds to opposite-letter mapping. Then apply the same mapping to each letter of EGO in sequence to form the coded word.

Step-by-Step Solution:
Using opposite-letter mapping: E ↔ V (E is 5th letter, V is 22nd) G ↔ T O ↔ L Now encode EGO: E → V G → T O → L So EGO → VTL.

Verification / Alternative check:
Check consistency with the example: P becomes K, and O becomes L, which are known opposite pairs. Since the same mapping is used for all letters, EGO must become VTL without any shifting or reordering.

Why Other Options Are Wrong:
SGD: corresponds to different mapping (like shifting) not opposite-letter substitution. VPU: would imply G→P which is incorrect in Atbash. MJN: does not follow opposite pairs for E, G, O. ETL: keeps E unchanged, breaking the substitution rule.

Common Pitfalls:
Using + or - shifts instead of opposite mapping, reversing the word order, or mapping using A=0 style offsets can lead to wrong codes.

Final Answer:
VTL