What phrase refers to what was to be demonstrated in an argumentative context?

The phrase "Q.E.D." stands for "quod erat demonstrandum," which is a Latin term meaning "which was to be demonstrated." It is traditionally used at the end of mathematical proofs or philosophical arguments to signify that the proof or argument has been successfully completed. In an argumentative context, employing "Q.E.D." indicates that the speaker has effectively demonstrated their point, allowing the audience to understand that the evidence provided substantiates the argument made.

The other terms hold different meanings and contexts: "quid pro quo" refers to a favor or advantage granted in return for something, which does not apply to demonstration; "res" can mean "thing" in Latin and is too vague for argumentative contexts; and "quantum" typically pertains to a measured quantity or level, often used in scientific contexts rather than in argumentation. Thus, "Q.E.D." is the most relevant phrase for indicating the completion of a demonstration in an argument.