The correct answer to this open question is the following.
Although this question does not include a specific reference about what experiment it is referring to, we can say that scientists have found that chewing gum helps to increase concentration and improves memory. Some scientists say that chewing gum increases psychological attention, allowing the individual to better focus on the task at hand. They even affirm that chewing gum helps to reduce stress, which allows people to concentrate and perform better. So chewing gum is good when you are studying for an exam.