Clara is in the "why" stage [wail]. Everything is "WHY?!" or "BUT WHHHHHHHHHY?". No answer will satisfy her.
This is our first proper time out with the why stage as at this age with Phoebe she wasn't talking. Wow, I just realised that, seriously when Phoebe was this age she had 10 words and preferred the point and shriek or just tantrum to attempting speech! Anyway by the time we got to the why stage with Phoebe she was much older and is easier to answer as she asks sensible questions instead of just "Why?".