Of all the areas of learning the most impo

问题：

Of all the areas of learning the most important is the development of attitudes. Emotional reactions as well as logical thought processes affect the behavior of most people.
"The burnt child fears the fire" is one instance. Another is the rise of despots like Hitler. Both of these examples also point up the fact that attitudes stem from experience. In the one case the experience was direct and impressive, in the other case it was indirect and cumulative. The Nazis were formed largely by the speeches they heard and the books they read.
The classroom teachers in the elementary school are in a strategic position to influence attitudes. This is true partly because children acquire attitudes from those adults whose opinion they respect.
Another reason is that pupils often delve somewhat deeply into a subject in school that has only been touched upon at home or has possibly never occurred to them before. To a child who had previously acquired little knowledge of Mexico, his teacher’s method of handling such a unit would greatly affect his attitude towards Mexicans.
The media through which the teacher can develop wholesome attitudes are innumerable. Social attitudes (with special reference to races and nationalities) science matters of health and safety, the very atmosphere of the classroom--these are a few of the fertile fields for the induction of proper emotional reactions.
However, when children come to school with undesirable attitudes, it is unwise for the teacher to attempt to change their feelings by cheating or scolding them. She can achieve the proper effect by helping them obtain constructive experiences. Finally, a teacher must constantly evaluate her own attitudes, because her influence can be harmful if she has personal prejudices. This is especially true in respect to controversial issues and questions on which children should be encouraged to reach their own decisions as a result of objective analysis of all the facts.

The word "harmful" in the last paragraph most probably means ______.

A. bad-affecting
B. ill-effective
C. widespread
D. irritating