Suppose you asked several people to tell you what their favorite pet might be. Many people would answer your question by saying dogs were their favorite.

Dogs can be trained in so many ways that they can become actual companions and friends to their owners. People have depended upon dogs for so many kinds of friendships. Some dogs are well-behaved house pets. Others are loyal watch dogs and protectors of valuable property. Hunters have trained their dogs to help find and retrieve game. Dogs are used to assist the physically challenged in many ways. These helping dogs are used as leader dogs for the visually impaired. They can also assist those bound to a wheelchair. Dogs have also been trained to help rescue people who have been lost or injured.

A dog is one of the most loyal of pets. This loyalty certainly makes the dog one of man's best friends.

Choose the sentence that best describes the main idea of the preceding paragraph.