The Swachh Bharat Mission - Urban certifies cities on a sanitation ladder: ODF, then ODF+, then ODF++. Each level has its own defined benchmark, and this question isolates the specific benchmark that defines ODF++.
- All households have piped water connection: Piped water supply coverage is tracked as a separate urban infrastructure benchmark, under missions like AMRUT, it is not the specific test used for ODF++ status.
- All households have rainwater harvesting systems: Rainwater harvesting concerns capturing and conserving stormwater, an entirely different issue from sewage and faecal sludge handling, so it plays no role in ODF++ certification.
- All sludge and sewage are safely managed and treated, with no discharge into the open environment: This is the exact defining condition for ODF++. The whole point of the "++" is to certify that faecal sludge and sewage do not end up untreated in open drains, water bodies, or open land, closing the loop that ODF and ODF+ do not fully address.
- All households have dry and wet waste segregation systems: Waste segregation is a solid waste management benchmark, assessed under the separate "Garbage Free City" star-rating system, not under the ODF++ ladder.
Because ODF++ is specifically about safe faecal sludge and sewage management with zero open discharge, only the third option describes its mandatory requirement.
Let's summarize:
- ODF: everyone has access to a toilet, no open defecation.
- ODF+: community and public toilets are functional and well maintained.
- ODF++: all sludge and sewage are safely managed and treated, with no discharge into the open environment, exactly option (C).
So the correct answer is option (C) only.