【单选题】

For laymen ethnology is probably the most interesting of the biological sciences for the very reason that it concerns animals in their normal activities and therefore, if we wish, we can assess the possible dangers and advantages in our own behavioral roots.Ethnology also is interesting methodologically because it combines in new ways very scrupulous field observations with experimentation in laboratories.

The field workers have had some handicaps in winning respect for themselves. For a long time they were considered as little better than amateur animal-watchers certainly not scientists, since their facts were not gained by experimental procedures: they could not conform to the hard-and-fast rule that a problem set up and solved by one scientist must be tested by other scientists, under identical conditions and reaching identical results. Of course many situations in the lives of animals simply cannot be rehearsed and controlled in this way. The fall flocking of wild free birds can’t be, or the homing of animals over long distances, or even details of spontaneous family relationships. Since these never can be reproduced in a laboratory, are they then not worth knowing about
The ethnologists who choose field work have got themselves out of this impasse by greatly refining the techniques of observing.At the start of a project all the animals to be studied are live-trapped, marked individually, and releaseD、Motion pictures, often in color, provide permanent records of their subsequent activities. Recording of the animals’ voices by electrical sound equipment is considered essential, and the most meticulous notes are kept of all that occurs. With this material other biologists, far from the scene, later can verify the reports. Moreover, two field observers often go out together, checking each other’s observations right there in the fielD、
Ethnology, the word, is derived from the Greek ethos, meaning the characteristic traits or features which distinguish any particular group of people or, in biology, a group of animals such as a species.Ethnologists have the intention of studying "the whole sequence of acts which constitute an animal’s behavior." In abridged dictionaries ethnology is sometimes defined simply as "the objective study of animal behavior," and ethnologists do emphasize their wish to eliminate myths.
The meaning of the underlined words in "the details of spontaneous family relationships" can be expressed as ______.A．natural family relationships
B．quickly occurring family relationships
C．animals acting like a natural family
D．animal family behavior that cannot be preplanned or controlled