Think about the article. Which of these is true about search-and-rescue dogs?

Scientists believe that search-and-rescue dogs can take the place of researchers.
Search-and-rescue dogs are better at tracking scents than humans or machines.
Search-and-rescue dogs have been trained to tally population sizes of threatened species.
Scientists know that search-and-rescue dogs are smarter than police dogs.

Search-and-rescue dogs are better at tracking scents than humans or machines.