The correct answer is C. The CSS styles defined in the parent list component are not shared with the child items. The study guide explicitly keys this Shadow DOM behavior.
The UX Designer must account for component-level style isolation when specifying how the custom parent and child LWCs should appear. In the scenario, the parent component represents the overall To-Do List, while separate child components represent individual To-Do items.
The answer key indicates that styling defined within the parent component cannot simply be assumed to apply inside each child component. Consequently, the designer and developer need to plan styling at the appropriate component level rather than expecting the parent's stylesheet to control every repeated child item automatically.
Option B states the opposite behavior by assuming that the parent's CSS is inherited by the child components.
Option A focuses on Light DOM, but the scenario specifically asks about the impact of the LWC's Shadow DOM structure, and the guide selects style separation as the relevant consideration.
The design implication is significant: component boundaries affect implementation. A visually consistent specification must account for how styles are scoped when a user interface is decomposed into multiple Lightning Web Components.
Study Guide reference/topics: LWC, Shadow DOM, CSS scope, parent-child components, SLDS.
==================================
