15 (A) Efforts are made to build mutual understanding and to avoid any misbehavior that might be devastating. (B) The size, weight, preference, and nature of both are taken into account for a good match. (C) After a few years of trial-and-error, it was decided that certain breeds are better guides than others. (D) Though trained to be obedient, they are also taught that sometimes they must disobey the owner’s command.