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.