Questions 14-17 are based on the following text.
 

    Dogs are one of the smartest animals and are often calles 'man's best friend'. As well as being a pet, many trained dogs also become professionals to help police, airport officials, and people with special needs. It is this special ability that has always been an attraction for experts to research dogs more scientifically and deeply. As reported in TIME, one of the experts who is interested in it was neuroscientist Gregory Berns from Emory University in Atlanta, United States. Not just studying their behavior, Berns specifically trained dogs to sit quietly inside Magnetic Resonance Imaging (MRI) so that the way their brain worked could be scanned and seen. Without being anesthetized or put to sleep, the fully awake dog was told to sit while the MRI scanner was checking their brain.

    From the scanning purpose, large hardware was needed so that the software could function optimally. The result of the scanning indicated that the size of the brain is the determining factor. The dog's brain size is relatively large. Human brain is considered very big, reaching a proportion of 1:50 of the average total body weight. The size of the dog's brain turned out to be 1:125 of the dog's total body weight. It is the ratio found in almost all types of puppies. In comparison with ther animals, the size of a lion's brain is slightly better at 1: 550 of the total body weight. SO, among other animals, the size of a dog's brain is indeed quite large and can accommodate more cognitive and affective development.

    Dogs are very sensitive to tones. From changes in tone, dogs can learn and distinguish human words. Bern's research aimed to find out how dogs learn human language: when dogs hear a word, it is just an auditory stimulation or does it have more meanings? He spent a year observing the brain activities of the dogs when they heard familiar words or unclear chatter. From the tone, dogs can learn to distinguish human words. As with human babies, puppies respond to human's high-pitched speech than low-pitched one. Researchers in New York and France also found that high notes really helped puppies learn words. But as adults, dogs no longer choose high octaves as they did when they were young.

(adapted from https://www.hipwee.com)

What is the main idea of the passage?