Which of the following is NOT a factor affecting filtration rate?

The correct choice indicates that electrical conductivity is not a factor affecting filtration rate. Filtration rate is primarily influenced by the physical characteristics of the water and the filtration system itself. Factors that affect how quickly water can pass through a filter include particle size, since smaller particles typically require more time to be trapped, and the type of filter media used, which can vary in porosity and surface area, subsequently impacting how efficiently water flows through. Water temperature can also affect viscosity; warmer water is less viscous and may flow through a filter more quickly.

Electrical conductivity, on the other hand, relates to the water's ionic content and is more associated with the water's chemical properties rather than the mechanics of physical filtration. Therefore, it does not directly influence the rate at which water is filtered through a medium in a typical filtration process. This distinction clarifies why electrical conductivity is the correct choice for being unrelated to filtration rate.