ANS:D - none of these.

Filtration rate typically does not depend on the pressure drop and area of the filtering surface. Here’s an explanation of why this is the case:

Understanding Filtration Rate:

1. Definition:
   • Filtration Rate: This refers to the rate at which filtrate (liquid passing through the filter) is produced per unit area of the filter medium or filter surface.
2. Factors Affecting Filtration Rate:
   • Resistance Factors: The filtration rate is primarily influenced by the resistance encountered during the filtration process. This resistance includes:
     • Cake Resistance: The accumulation of solids (cake) on the filter medium increases resistance.
     • Medium Resistance: The inherent resistance of the filter medium itself to the passage of liquid.
     • Septum (Supporting Medium) Resistance: This is the structural support for the filter medium, influencing the flow of liquid through the filter.
3. Factors Not Affecting Filtration Rate:
   • Pressure Drop: While pressure drop affects the driving force for filtration, it does not directly determine the filtration rate. Instead, it affects the flow dynamics and efficiency of the filtration system.
   • Area of Filtering Surface: The size of the filtering surface (filter area) affects the total amount of filtrate produced but does not dictate the rate per unit area (filtration rate).
4. Other Considerations:
   • Properties of Cake and Filtrate: These properties influence filtration efficiency and the quality of the filtrate but do not directly determine the filtration rate per se.

Conclusion:

Based on the factors influencing filtration rate, the correct answer to the statement "Filtration rate does not depend upon..." is pressure drop and area of filtering surface. These factors affect other aspects of filtration dynamics but not the filtration rate itself, which is primarily governed by the resistance encountered during the filtration process.