When two 8-bit numbers A7 … A0 and B7 … B0 in 2’ s complement representation (with A0 and B0 as the least significant bits) are added using a ripple-carry adder, the sum bits obtained are S7 … S0 and the carry bits are C7 … C0. An overflow is said to have occurred if

• A. the carry bit C7 is 1
• B. all the carry bits (C7 …, C0) are 1
• C. (A7.B7.S̅7 + A̅ 7.B̅ 7.S7) is 1
• D. (A0.B0.S̅0 + A̅0.B̅0.S0) is 1