Which of the following is a contact force?

A. Air resistance

B. Magnetic force

C. Gravity

D. Electrical force

The contact force is indeed caused by "Contact".

Air resistance is basically a type of friction, which is apparently present providing two object contact.

The rest selections are all interaction force, which is not necessarily caused by contact.

Air resistance is a contact force as the air comes in direct contact with the object and pushes against it. Magnetic force - you can attract a magnet without touching it. Gravity, works on you when you are not in contact with the earth, pulling you down. Electrical force, between 2 electrons when not in contact.