What is the purpose of the State Frame Delimiter byte in a frame?

A. It provides physical timing for the frame following.
B. It divides the data and the physical timing portion of the frame.
C. It provides a means for the receiving node to know when databegins.
D. It delimits the destination and source MAC address.

C. The preamble is 7 bytes of alternating 1s and 0s at a frequency that matches the bandwidth of the link. It is important to note that the 1s and 0s pattern starts with a 1 and ends with a 0 for 7 bytes (10101010). The SFD has an extra lower bit signaling the end of timing and the start of data (10101011).