Read the following article and select the best answer. Article: Watching a 3D movie can more than double the concentration powers and cognitive processing of children, a new research claims. A study made by visual technology firm RealD and led by child psychologist Dr Richard Woolfson suggests that childrenaged between 7 and 14 experienced twice the cognitive processing speed and performed better in testing after watching 20 minutes of a 3D film. This is despite suggestions that attention spans in children have shortened in the last decade due tounlimitedto access to entertainment, including on-demand TV, gaming and social media. A 2015 study claimed that watching 3D content had a similar effect to brain-training exercises. Consumer psychologist Mr Fagan said that the increasedstimulation found in watching something in 3D "exercised" the brain and improved performance in the short term. "3D films can play the role of 'brain-training' games and help to make children 'smarter' in the short term," he said. "The shortening of response times after watching 3D was almost three times as big as that gained from watching 2D; in other words, 3D helps children process aspects of their environment more quickly. This is likely to be because 3D is a mentallystimulatingexperience which 'gets the brain's juices flowing'." The experiment saw children given a range of cognitive tests before watching 20 minutes of a movie in either 2D or 3D and being tested again. The results showed those who saw the 3D content reacted faster and performed bettering the second round of testing. Mental engagement also rose by 13% among 3D watchers. Child psychologist Dr Woolfson added that "supportive parenting" and regularly listening to classical music can also aid a child's memory. Question: The reason why children perform better after watching a 3D movie is that _ . - a 3D movie makes their brain active - a 3D movie is more exciting than a 2D movie - children enjoy watching a 3D movie - children like the experience which "gets the brain's juices flowing"
Answer:
a 3D movie makes their brain active