This is a simple question without a very straightforward answer in this case.
Oftentimes individuals with ADHD do struggle to keep their attention on one thing at a time and are observed to be restless or fidgety during times they are expected to sit still.
However, ADHD can also cause individuals to hyperfocus on a specific task (such as becoming overly fixated on watching TV) but can lead to issues with the ability to also process other external sensory stimuli such as someone asking them a question while they are watching TV and in these instances, children with ADHD don’t answer as they are unable to focus on multiple stimuli at once.