Final answer:
Instrument procedures in aviation are based on the magnetic track, which is in relation to the Earth's magnetic field. Option (a) magnetic is the correct answer for the initial question. It's also true that one should avoid placing credit cards near permanent magnets to prevent demagnetization.
Step-by-step explanation:
The subject of this question relates to instrument procedures in the field of aviation navigation. When discussing the basis of these procedures, we are referring to the reference system that the instruments use to guide aircraft during various phases of flight, especially in poor visibility or instrument meteorological conditions.
Instrument procedures are based on the magnetic track. The magnetic track refers to the path of an aircraft in relation to the Earth's magnetic field. It is the direction of the aircraft's path at any point measured in degrees from magnetic north.
To answer the question, option (a) magnetic is correct. Furthermore, to address the Critical Thinking Item pertaining to magnetic fields and magnetic strips: it is true that it is not recommended to place credit cards with magnetic strips near permanent magnets due to the potential for the magnetic field to demagnetize the strip, rendering the card unusable.