Concept:Specialisation is the degree of structural and functional adaptation shown by an organism for particular life activities.
Explanation:Among the listed organisms, Paramecium shows the highest level of specialisation.
It has cilia for movement and feeding, a gullet for food intake, food vacuoles for digestion, and contractile vacuoles for osmoregulation.
It also contains two distinct nuclei: a macronucleus and a micronucleus.
Amoeba is much simpler, using only pseudopodia for both movement and feeding.
Spirogyra is a filamentous alga with simple cellular organisation.
Rhizopus is a mould with comparatively undifferentiated hyphae.
These specialised structures make Paramecium the most adapted organism among the given options.
Answer:A. Paramecium