I also want to know. This was my answer and it was marked as wrong. I think the correct is with 'z'.
September 19, 2018
They are both correct: https://grammarist.com/spelling/apologise-apologize/.
March 8, 2019
It can be either passive or active
- Nós desculpamos voce = we forgive you
- Você me desculpa? = Do you forgive me?
May 22, 2019