The sentence "the binder was picked up" is in the Passive Voice.
Explanation:
The Passive Voice has the following structure:
subject + to be (auxiliary) + main verb (past participle)
It is used to emphasize the person or thing that is the recipient of the action described by the verb rather than the person or thing that actually performed it. An example of a sentence in the passive voice is: My house was painted recently.
The sentence "The binder was picked up" is in the passive voice, as its structure shows. The same sentence, in the active voice, would be "Someone picked the binder" or "They picked up the binder".
