Final answer:
The overflow critical path in a 4-bit ripple carry adder contains four XOR gates.
Step-by-step explanation:
In a 4-bit ripple carry adder, the overflow critical path refers to the path that carries the overflow bit from the highest bit to the next higher bit. The overflow bit is the result of adding two positive numbers and getting a negative result, or adding two negative numbers and getting a positive result.
In a 4-bit ripple carry adder, the overflow critical path consists of 4 XOR gates, with each XOR gate connected to the carry-out of the previous bit.
Therefore, the overflow critical path in a 4-bit ripple carry adder contains 4 XOR gates.