Ripple-adder carry behavior: In an n-bit ripple adder, the carry output of each stage is claimed to provide an additional SUM output bit of that same stage. Judge this statement carefully.

Introduction / Context:
Ripple adders chain 1-bit full adders so that each stage’s carry out feeds the next stage’s carry in. Understanding the role of carry versus sum bits prevents architectural misunderstandings and timing misinterpretations in digital arithmetic.

Given Data / Assumptions:

• Each 1-bit full adder produces SUM (Si) and CARRY OUT (Ci+1).
• Inputs at stage i: Ai, Bi, and Ci (from previous stage).
• Overall n-bit addition yields an n-bit sum plus a final carry (n+1th bit).

Concept / Approach:
The SUM bit at a stage is Si = Ai XOR Bi XOR Ci. The CARRY OUT is Ci+1 = Ai*Bi + Bi*Ci + Ai*Ci. The carry is not an additional SUM output of that stage; instead, it becomes the carry input of the next higher-order stage. Only the final carry out (from the most significant stage) can be viewed as an extra high-order bit of the overall result.

Step-by-Step Solution:

Verification / Alternative check:
Add 1111 + 0001: the four SUM bits are 0000 with a final carry 1. The single extra bit appears only at the most significant end, not at every stage.

Why Other Options Are Wrong:
“Correct” confuses carry propagation with sum generation. References to “least-significant stage” or “end-around carry” do not change the fundamental role of stage carries in a ripple adder.

Common Pitfalls:
Treating carry chains as additional data outputs per stage; miscounting result width; ignoring that carry is positional and feeds only the next stage.

Final Answer:
Incorrect