Final answer:
The question pertains to the engineering design of domed strainers for roof drains, focusing on preventing blockage by debris. The correct height is unspecified, but their design typically prevents clogging by allowing water to flow around debris.
Step-by-step explanation:
The question regarding the height of domed strainers for roof drains touches upon a practical aspect of architectural design and engineering. The correct answer to the height needed so that debris against the strainer will not prevent the function of the drain is not clearly provided within the question. However, the typical design for domed strainers usually includes sufficient height for the purpose of allowing water to drain effectively even when debris is present. This ensures that water can flow around or over the debris, instead of being blocked. Without the exact measurement options given in the question, it's not possible to provide the correct numerical answer. Nevertheless, the purpose of these raised strainers is to avoid clogging and ensure that drainage systems operate efficiently during varying weather conditions.