Finally Mandana kept saying I don't want you to explain. Because she was getting irritated with the thought of how wrong her own decision was.
If she was so selfless then why she didn't press the button. The moment she didn't press itself meant she wanted to target someone else. If she was so selfless and wanted to do the wok herself then there was no need to get annoyed at Rochelle. That means she had a cunning motive and the more and more Rochelle kept repeating it she was worried people will see through her cunning mind.
But she was always saying since beginning that she's not here for friendships so what's her complaint? That means her plan failed miserable where she probably was thinking to target someone else.
Well done Rochelle for exposing the sly fox.