Study the given figure showing how water is made pure before it reaches our home and identify P, Q, R and S.

• A. P Q R S  Mixing tank    Pump Settling tank       Filter   
• B. P Q R S  Pump         Mixing tank        Settling tank       Filter   
• C. P Q R S  Pump         Settling tank       Mixing tank       Filter   
• D. P Q R S  Filter         Mixing tank       Settling tank       Pump