Complex sentence: Prompts are often categorized into a prompt hierarchy from most intrusive to least intrusive, although there is some controversy about what is considered most intrusive, those that are physically intrusive or those that are hardest prompt to fade (e.g., verbal).
Split into simpler sentences: Prompts are often categorized into a prompt hierarchy from most intrusive to least intrusive. There is some controversy about what is considered most intrusive: physically intrusive versus hardest prompt to fade (i.e., verbal).