The receiving computer checked the checksum of a frame. It had been damaged during transfer, so it is discarded. At which layer of the OSI did this occur?

A. Physical layer
B. Data Link layer
C. Network layer
D. Session layer

B. The Data Link layer is responsible for checking the FCS, or Frame Checking Sequence, which is a checksum of the frame. This occurs on the MAC sublayer of the Data Link layer.