What's less obvious is how smart they are. After studies over the past decade, they've shown abilities previously thought to exist only in humans. Take the scrub jays (a kind of bird). A few years ago, Cambridge University professor Nicky Clayton, PhD, found that these birds can be surprisingly devious (狡猾的), remembering not only what foods they've hidden but where, how long ago, and whether anyone else might have noticed. "If another bird was watching, they'd wait until that bird was gone and then move the food," Clayton says. Another recent experiment hints that monkeys experience regret when they make the wrong choice and miss out on a treat. Researchers say brain scans suggest the animals were having regretful thoughts. "I knew monkeys were smart, but I didn't think they were that smart," says Michael Platt, PhD, who led the study. But perhaps no animal has done more to change conventional notions than Alex, an African gray parrot. A 30-year research subject for scientist Irene Pepperberg, PhD, Alex altered the belief that parrots were simple mimics (模仿者). He was constantly being tested; when he was tired of it, he would tell Pepperberg, "Wanna go back"—to his cage. If the request annoyed her, Alex would say, "Sorry." The parrot toyed with her cruelly, and one afternoon, he showed an apparent grasp of something only humans and a few apes (类人猿)had been known to understand: the concept of zero. Which is true according to Paragraph 1?

Animals can be remarkably devoted. What's less obvious is how smart they are. After studies over the past decade, they've shown abilities previously thought to exist only in humans.

Take the scrub jays (a kind of bird). A few years ago, Cambridge University professor Nicky Clayton, PhD, found that these birds can be surprisingly devious (狡猾的), remembering not only what foods they've hidden but where, how long ago, and whether anyone else might have noticed. "If another bird was watching, they'd wait until that bird was gone and then move the food," Clayton says.

Another recent experiment hints that monkeys experience regret when they make the wrong choice and miss out on a treat. Researchers say brain scans suggest the animals were having regretful thoughts.

"I knew monkeys were smart, but I didn't think they were that smart," says Michael Platt, PhD, who led the study.

But perhaps no animal has done more to change conventional notions than Alex, an African gray parrot. A 30-year research subject for scientist Irene Pepperberg, PhD, Alex altered the belief that parrots were simple mimics (模仿者). He was constantly being tested; when he was tired of it, he would tell Pepperberg, "Wanna go back"—to his cage. If the request annoyed her, Alex would say, "Sorry." The parrot toyed with her cruelly, and one afternoon, he showed an apparent grasp of something only humans and a few apes (类人猿)had been known to understand: the concept of zero.

Which is true according to Paragraph 1?

• A. Animal study proved animals were devoted.
• B. Animals are obviously very smart.
• C. Some abilities of humans exist in animals.
• D. Animal study was slow in the past decade.