8. Consider a data-link layer protocol that uses byte-stuffing. This protocol consists of a single, variable length, payload field. Assume that this protocol is used over an unreliable channel that occasionally changes bytes into flag bytes. Which of the approaches below cannot be used by the sender to let the receiver detect (most of) these errors? A. Adding a checksum to the end of every message. B. Adding a Cyclic Redundancy Check (CRC) to the end of every message. C. Adding escape bytes within every message. D. Adding the frame-length to the start of every message