Decode the uppercase string using a Caesar shift of −6, then output in lowercase. Given: XDMJRA

Introduction / Context:
Uniform backward Caesar shifts decode each character by a fixed amount. Here we use −6.

Given Data / Assumptions:

• Cipher: Caesar −6.
• Input: XDMJRA.

Concept / Approach:
Shift each letter back by 6 positions modulo 26.

Step-by-Step Solution:

Verification / Alternative check:
Re-encoding “algpkj” with +6 returns “xdmjra”.

Why Other Options Are Wrong:

• ymswtx, nstryj, vbfnic: These represent different net transforms and do not inverse to XDMJRA with +6.

Common Pitfalls:
Inconsistent alphabet indexing between letters (A=0 vs A=1). Stick to one scheme.

Final Answer:
algpkj