Overflow detection for binary number addition and subtraction.

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Group of answer choices

If the sum of two $$ve numbers yields a $+$ve result, the sum has overflowed.

If the sum of two $+$ve numbers yields a $$ve result, the sum has overflowed.

Overflow is detected when the xor of the carry out of the two MSB is $1($i$.$e$.,*$C$4$ XOR C$3)=1)$

The sum of $+$ve and $-$ve numbers must have no overflow.

None is a correct answer.