The correct answer for the common name "slipper animalcule" is option 1, Paramecium. Paramecium is a single-celled organism commonly found in freshwater habitats. It is characterized by its slipper or shoe-like shape, which gives it the name "slipper animalcule". Paramecium is a eukaryotic organism that belongs to the ciliate group and is known for its fast and jerky movements by beating its hair-like projections called cilia. It feeds on bacteria and smaller microorganisms by creating a current with its cilia and sweeping them into its mouth-like opening called the oral groove. Paramecium plays an important role in the ecosystem by consuming bacteria and recycling nutrients.