What is the major cause of mechanical delay in a hard disk?

Correct answer: The read head must reach the correct location and wait for platter rotation

A traditional hard disk drive stores data on rotating magnetic platters. To read a requested block, its actuator must move the read/write head to the correct track, and the platter must rotate until the desired sector arrives. These seek and rotational-latency movements create mechanical delay. Therefore, option A is correct; the other choices do not affect disk positioning.