• Types of Solar Stills in Solar Distillation:
• Standard passive and active solar distillation units include:
• Single-effect basin solar still: Simple airtight basin covered by inclined glass.
• Tilted-tray solar still: Multiple shallow stepped trays inclined toward the sun.
• Wick-type solar still: Utilizes capillary action through porous blackened fabric wicks.
• Multiple-effect solar stills are industrial active multi-stage distillation systems requiring external heat exchangers rather than standalone passive solar still classifications.
• Conclusion: Multiple effect solar still (Option 2).

Correct option: (2) Multiple effect solar still