【单选题】

By saying that "observers are waiting for the dominoes to start falling", the author means that
A．observers are taking a wait-and-see attitude towards the future of euthanasia.

B．there is a possibility of similar bills being passed in the U.S. and Canada.
C．observers are waiting to see the movement end up in failure.
D．the process of the bill taking effect may finally come to a stop.