Select every form that can fill the gap in this past simple sentence: "The experiment ____ the theory beyond doubt in 1954."

Erklärung

The past simple of this verb is proved, and that is the only shape the slot accepts. Proven is a genuine form of the same verb, standard after has or have and before a noun as in a proven method, and American English uses it freely in those positions, but it cannot serve as a plain past tense; prooved and provened are not English forms at all.