Final answer:
The correct answer is that a platter spins and an arm moves to access data on a hard disk drive. These components are essential for the operation of the drive, as the arm positions the head to read or write information on the spinning platter. Option b is correct.
Step-by-step explanation:
When a hard disk drive is being accessed, the platter spins and the arm moves until the head is over the proper location on the disk. The platter is the component that stores information magnetically on its surface, and it rotates around a central spindle. The arm, which holds the read/write head, moves radially over the surface of the spinning platter to read from or write data to the correct location. Hard disk drives work on principles that are similar to those used in audio and video magnetic tapes, but computer hard drives operate at much faster speeds and use digital information.
In related physical principles, an object that is spinning, like a hard disk platter or a top, experiences properties like angular momentum and precession, particularly when external forces are applied. For example, when a spinning disk is inside a device and you attempt to rotate the device, you'll notice resistance due to the gyroscopic effects. This same phenomenon is observed with an Earth spinning on its axis, a ceiling fan, or a toy top.