Are or Is?

In this instance, should I use the word "are also revealed" or "is also revealed"?

It's in the second sentence of this section, I just included the first to contextualise it.

Thanks in advance!
Emma

The former can be seen through Bromden who pretends to be deaf and dumb, having been silenced by society, and therefore has lost one of the essential qualities of being human: the will to communicate with the world. This loss of the qualities which make the individual human are also revealed through Billy who is shamed by nurse Ratchet after having sex when she threatens to tell his mother, and it is this threat which prompts his suicide.