Final answer:
Magnetism is a force that can both attract and repel objects without physically touching, making it the correct answer choice.
Step-by-step explanation:
Magnetism is a force that certain kinds of objects, which are called magnetic objects, can exert on each other without physically touching. A magnetic object is surrounded by a magnetic 'field' that gets weaker as one moves further away from the object.
Gravity is the force responsible for attracting objects towards each other, such as the gravitational pull of Earth. It can also repel objects, although this repulsion is not noticeable in everyday situations as the force of gravity between macroscopic objects is very weak compared to other forces.
Therefore, the correct answer is A. magnetism, as magnetism is a force that can both attract and repel objects without physical contact.