In 2's-complement addition, overflow:

In 2's-complement addition, overflow is possible only when two operands with the same sign produce a result with the opposite sign. Equivalently, overflow occurs when the carry into the sign bit differs from the carry out of the sign bit. If one operand is positive and the other is negative, their sum lies between the two values and remains representable, so overflow cannot occur. Therefore, the correct statement is that overflow cannot occur when a positive value is added to a negative value.