Which of the following statements is/are correct? 

I. Overflow in two's complement addition can be detected by examining only the carry out of the most significant bit. 

II. When converting an unsigned integer to a larger type, zero extension is used to preserve its value.

 III. In Binary-Coded Decimal (BCD) representation, each decimal digit is encoded separately using four binary bits. 

IV. In a byte-addressable system, the effective address calculation is dependent on instruction length

1. Overflow Detection (Signed vs. Unsigned)In digital circuits, the CPU must distinguish between a simple carry and an actual overflow.Unsigned: Overflow occurs if there is a carry-out of the MSB ($C_{out} = 1$).Signed (2's Complement): Overflow occurs if the result exceeds the range (e.g., adding two positive numbers yields a negative result). The logic gate used for this is $V = C_{in} \oplus C_{out}$ (XOR of the last two carries).2. Data ExtensionWhen a computer moves data from an 8-bit register to a 16-bit register:Zero Extension (Unsigned): Pads the upper bits with 0. (e.g., 1010 becomes 0000 1010).Sign Extension (Signed): Copies the MSB (sign bit) to all new positions. (e.g., -6 as 1010 becomes 1111 1010).3. BCD (Binary-Coded Decimal)BCD is often used in electronic systems where numeric values need to be displayed (like digital clocks or calculators) because it is very easy to convert each 4-bit "nibble" directly into a single decimal digit. However, it is less efficient for mathematical computations than pure binary.