Question

multiple choice 1 point
what is true about forces?
forces always occur in pairs.
forces always occur alone.
forces can sometime occur in pairs.
forces can only occur in pairs if the objects have a similar mass.

Explanation:

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. This means that forces always occur in pairs. For example, when you push a wall (action force), the wall pushes back on you (reaction force). The other options are incorrect. Forces do not always occur alone (as per the law of action - reaction). They do not "sometimes" occur in pairs (it's a fundamental law, not a sometimes - situation). And the occurrence of force pairs has nothing to do with the masses of the objects (the law holds regardless of mass).

Answer:

Forces always occur in pairs.