Step 1: Recall Harappan urban planning.
The Harappan cities were well-planned with a citadel at the core, which housed important structures.
Next came the lower town where common people lived.
Around these were fortification walls for defense.
Finally, moats were constructed at the periphery in some settlements.
Step 2: Arrange from core to periphery.
Core → Citadel (C).
Next → Lower town (D).
Then → Fortification wall (B).
Periphery → Moat (A).
Step 3: Verify with options.
This sequence matches option (D).
Step 4: Conclusion.
Correct answer is (D) C, D, B, A.