Select the correct text in the passage.
Which detail from paragraphs 6-9 refines the central idea?
(6) Clinical psychologist Domenic Greco worked with biofeedback therapy - which can be based on anything from brainwaves to
heart rate - since the early 1980s. Around 2000, he and his son Devon exclusively licensed aspects of NASA's system, including
the engagement index, and founded CyberLearning Technologies, using video games to help users improve control over their
concentration. The SMART BrainGames system, released in 2003, made it harder to control the play as the user's attention
wandered.
(7) But the Grecos wanted to move beyond video games and bring the technology to bear on real-life activities. In the months
before Domenic's death in 2013, the father-son team came up with a solution: apply the same neurofeedback technology to smart
glasses that users could wear while performing any task at all. The glasses would darken as the user became distracted,
providing a real-time incentive to stay focused.
(8) After his father's death, Devon shuttered Cyberlearning and almost immediately started Narbis, of Ambler, Pennsylvania, to
work on the smart glasses.
(9) While several companies have tried different twists on neurofeedback, Pope said this one is different because "there's an
incentive involved - you're motivated to make the lenses clear, so it uses reinforcement."