Which of the following methods is used to detect double errors?

To detect double errors effectively, one must use a method that can identify changes in multiple bits simultaneously. Parity schemes like Odd or Even Parity are limited because they only check if the total number of set bits is odd or even. If two bits flip, the parity remains unchanged (e.g., an even number of errors preserves even parity), making single-bit error detection the maximum capability for these methods. In contrast, Cyclic Redundancy Check (CRC) employs polynomial division to generate a checksum that is highly sensitive to multiple bit errors. This mathematical approach ensures that even if two bits are corrupted during transmission, the resulting checksum will differ from the expected value, allowing for reliable detection. Therefore, CRC is the superior choice among the options provided for detecting double errors.