Which factors can significantly affect septic system design?

The answer is centered on the key elements that have a direct impact on the functioning and effectiveness of a septic system. Soil type is crucial because it determines how well effluent will be absorbed into the ground. Different soil types have varying levels of permeability, which affects how quickly and effectively wastewater can be filtered and decomposed. Lot size is significant as it influences how much space is available for the septic system and the drain field, which needs to meet certain area requirements based on the expected volume of wastewater. Expected wastewater volume is essential since it informs the size and capacity of the septic system; larger homes or properties that generate more wastewater will require systems designed to handle that increased load.

While other choices mention relevant aspects like climate and local regulations, they do not address the fundamental factors that dictate the design specifics of the septic system itself. For instance, aesthetics and landscaping, although they may play a role in installation planning, do not directly affect the septic system's operational design. Thus, the combination of soil type, lot size, and expected wastewater volume makes option B the most comprehensive and essential for understanding the septic system design considerations.