Final answer:
The word "upset," when used to mean defeat, is best matched by the term "overthrow," which refers to the defeat or toppling of a person or group in power.
Step-by-step explanation:
The word "upset" has multiple meanings, but when used in the context of defeat in a competition or battle, the synonym that matches is "overthrow". The correct answer to the question "Which of the following matches the word "upset" (meaning defeat)?" is d) overthrow
"Overthrow" implies the defeat or toppling of an existing power or authority, similar to how "upset" can be used to describe an unexpected defeat, often of someone who was anticipated to win.
Victory and conquest imply a successful outcome, whereas surprise denotes an element of the unexpected which could be part of an upset but does not specifically indicate defeat.