A brown and white dog walks down a ramp toward a pool of water in which a green tennis ball floats .
It is impossible that a terrier is trying to get to the ball his owner accidentally threw in the pool .
It is impossible that a terrier is trying to get to the ball his owner accidentally threw in the pool .
There is a better than even chance that a terrier is trying to get to the ball his owner accidentally threw in the pool .
A terrier is trying to get to the ball his owner accidentally threw in the pool .