What? (wouldn't let me just say what so ignore this part its just a filler text) =^-^=
Nikita is the only witness to see you doing it but she made it up
To prove your innocence you would have to been with other people they would serve as witness saying you didn't do it even when you know you didn't in order to prove your innocence.
I'm not sure if it answers your question
A and b are correct for this problem.
