Birds don’t need lessons in building nests. Fish don’t need coaching to learn how to swim. All animals have instincts. They’re born with natural abilities to do certain things. Wild animals also learn by copying their parents and practicing. And pets learn through training.
But instincts and training aren’t the only keys to animals’ behavior. Scientists say animals’ thoughts and feelings also influence their actions. Animals often make choices, plans, and sensible changes. They can help others and solve problems. Some even make and use tools!
If animals could talk, what would they say about their thoughts and feelings? A gorilla (大猩猩) born in captivity (关在笼子里) has helped answer that question. Koko, a gorilla, was taught to use sign language . She has learned hundreds of words!
Koko once had a pet cat she named All Ball. “Koko love Ball,” she signed. “Soft good cat.” One time, she blamed the cat for biting her by signing “You bad dirty toilet!” When her pet died, Koko cried. “Sad for sleeping cat,” she signed.
Koko calls herself “fine animal gorilla”. She uses sign language to argue, joke, and ask and answer questions.
“Most animals can’t use words to tell us their thoughts,” says Dr. Jonathan Balcombe. “But Koko shows us that animals have their own ideas and feelings.” Dr. Balcombe is a scientist at the Humane Society of the United States. He says there’s even more to discover about animals through field studies. In field studies, people watch animals in their natural environment.
“Scientists who study animals’ natural behaviors learn how animals live and think,” Balcombe says. “That knowledge can help others respect every animal who shares the planet with us.”
The underlined word “instincts” in the first paragraph probably refers to the ability that _____.

A．animals copy their parents	B．animals learn by practicing
C．animals are born with	D．animals learn through training