Is this sentence written in active or passive voice The apples were peeled and quartered?

Passive voice

This is a passive sentence. We can't tell from this sentence who peeled and quartered the Apples.

Compare with this active sentence - (we know who does the action):

Jason peeled and quartered the Apples

The Apples were peeled and quartered (by Jason)

In passive sentences the agent can be left out or put at the end of the sentence using by.