Once a baby cries, the parents will go to see what happened as soon as possible. According to a new study, a baby's cry can make adults react  very quickly, even if they are not related. Oxford University researchers used the classic game whack-a-mole for the study.  Whack-a-mole  requires people to hit one of nine buttons  . The players must react as quickly as they can to whichever of the buttons lights up at random . It is a game that requires speed and accuracy ( ). The study included 40 men and women volunteers aged 19 to 59. Some of them had sons or daughters but none had a baby at the time. They played whack-a-mole after listening to different sounds, including babies crying, the crying of adults in trouble and birdsong played at a similar pitch to the babies' cries. The volunteers' scores were higher after listening to the sound of crying babies. Men and women had similar scores overall. The results showed that a crying baby gets special attention. "Few sounds make people react quite like the cry of a baby," said Morten Kringelbach of Oxford's psychiatry  department, who led the study. "For example, it's almost impossible to ignore(,) crying babies on planes. This is true even though there are so many other noises around." He added that a baby's cry can increase adults' heart rate and blood pressure. This is understandable, because in the course of human evolution  , taking care of babies has always been an important job for adults. When a baby is hungry or feeling bored or unwell, it will cry. As a result, human brains and bodies develop a special reaction to a baby's cry. According to the passage, a baby's cry   _  .
has the same pitch as birdsong is the noisiest sound there is can increase adults' heart rate and blood pressure is good for its health