【单选题】

Questions 57 to 61 are based on the following passage.

Protests at the use of animals in research have taken a new and fearful character inBritain with the attempted murder of twoBritish scientists by the terrorist technique of the pre-planted car-bomB、
The research community will rightly be alarmed at these development, which have two objectives: to arouse public attention and to frighten people working in research with animals. The first need is that everything should be done to identify those responsible for the crimes and to put them on trial. TheDefence Research Society has taken the practical step of offering a reward of 10,000 pounds for information leading to those responsible, but past experience is not encouraging. People are unlikely to be tempted by such offers. The professional police will similarly be confronted by the usual problem of finding a needle in a haystack.
That is why the intellectual community inBritain and elsewhere must act more vigorously in its own defence. There are several steps that can be taken, of which the chief one is to demand of all the organizations that exist with the declared objectives of safeguarding the interests of animals that they should declare clearly where they stand on violence towards people.And it will not be enough for the chairman and chairwoman of these organizations to utter placatory statements on behalf of all their members. These people should also undertake that it will be a test of continuing membership in their organizations that members and would-be members should declare that they will take no part in acts of violence against human beings.Even such undertakings would not be fully effective: people, after all, can lie.But at least they would distinguish the organizations entitled to a continuing voice in the dialogue with the research community about the rights of animals in research from the organizations that deserve no say.
According to the author, the word "placatory" means ______.A．encouraging
B．defensive
C．rebellious
D．comforting