What is the term for a response that disproves the opposing argument?

The correct term for a response that disproves the opposing argument is "refutation." Refutation involves providing evidence or reasoning that disputes or contradicts the claims made by the opposing side. This process strengthens one's own argument by showing why the argument against it is invalid, thus effectively dismantling the opposing viewpoint.

A rebuttal often refers to the act of responding to an argument but may not always focus on complete disproof. It can involve presenting an argument or reasoning that supports one's own claims without necessarily disproving the other side. A counterclaim presents an alternative position or argument rather than directly disproof. An assertion is simply a confident statement or declaration and does not carry the weight of disproving another argument.