Possibility and Probability

1)I think we need to leave ........ the possibility that Simon has decided not to come to the party.

a) open
b) vacant
c) free

2) Your dog ate your homework? That's a ........ story!

a) realistic
b) possible
c) likely

3)There's a ........ chance I won't be at work tomorrow. I might have to stay at home to wait for a delivery.

a) fine
b) slim
c) thin