Which of the following is a non-contact force?
A) Muscular
B) Electrostatic attraction
C) Elastic spring force
D) Friction force

Hint: A non-contact force is defined as any force that does not require physical contact to act on. The opposite of a non-contact force is a contact force. Contact force requires contact between the two contact surfaces with some motion to occur.

Complete step by step solution:
From the given options, we can observe that all the options except electrostatic attraction need contact to occur. In the case of muscular force, we need contact to lift or apply force on our muscular system which is why it is a contact force. Frictional force occurs only when there is contact between two surfaces.

In the case of a moving body, the friction force is in the opposite direction of the moving body, which requires contact. In the case of elastic spring force, the force occurs only when the spring is being compressed, so it is also a contact force. Lastly in an electrostatic attraction, there is no contact required to feel the force of attraction between the two bodies. When we comb our hair and get the comb close to small pieces of paper, the pieces of paper get stuck to the comb. This is a consequence of electrostatic attraction. There is no contact between cob and paper yet the force occurs hence it is a non-contact force.

Option (B), electrostatic attraction is the correct answer.

Note: When it comes to classifying these types of questions always remember that a push or pull required force is the contact force on the other hand a repulsion or attraction force is always the non-contact force.