<prompt> True about slow sand filter is -Occupies less spaceMore expensiveRequires longer durationSand size 0.4-0.7 mm  <response>: Option A - wrong, slow sand filter occupy more space Option B - wrong, it is less expensive Option C - correct, rate of filtration is very slow 2-3m.g.a.d. hence takes longer time Option D - wrong, effective sand size in slow sand filter is 0.2-0.3 mm PARK TB 25th edition pg 773 