What is a secondary storage medium that uses magnetic techniques to store and retrieve data on disks or tapes coated with magnetically sensitive materials?

The correct answer to the following question will be "Magnetic medium".

Explanation:

Some storage device that portrays details or information using magnetic patterns is called a magnetic device.

Magnetic tape, and hard drives are the commonly used magnetic storage devices. This will be the method by which magnetic methods are used to hold and retrieve information on tapes.

So, it's the right answer.