Final answer:
Non-communicating hydrocephalus is the condition where the flow of CSF is blocked, causing a buildup due to the narrowing of the passageways that connect the brain's ventricles.
Step-by-step explanation:
The form of hydrocephalus characterized by a narrowing of the passageways that connect the ventricles, leading to CSF buildup, is Non-communicating hydrocephalus (A). In Non-communicating hydrocephalus, the flow of cerebrospinal fluid (CSF) is blocked along one or more of the narrow passages connecting the ventricles, which are the areas of the brain where CSF is produced and circulates. This blockage prevents CSF from moving freely through the system, causing a buildup of fluid, which can lead to increased pressure on the brain and may result in a range of neurological problems if not properly treated.