You can try "plait guilty with explanation". I belieave there is such a choice at the back of the ticket.
You wil be request to show up at a court and explanation why you parked there. If the judge thinks that you have some ground, your ticket may be waived or reduced. Reasons can include something like dropping an old lady.
It does hurt to try. The worst is that the judge refuse your explanation and you pay the whole amount. You just several hours at the court house.