Answer:
3. Pellicle
Step-by-step explanation:
The paramecium and amoeba are both protists organisms that are unicellular and possess an eukaryotic cell. They are both classified under the Domain Eukarya and Kingdom Protista. They have similar structural characteristics but possess few differences. According to the question, they both possess the following structures:
1. Cytoplasm, which is the intracellular fluid that contains all other cellular organnelles and substances e.g enzymes.
2. Food vacuoles, which is an enclosed structure that can out food breakdown for absorption.
3. Nucleus, which is a structure that houses the genetic material (DNA) in both organisms. This is the reason both the paramecium and amoeba are classified as eukaryotes.
Based on the options provided in the question, the structural difference between amoeba and paramecium is the PELLICLE. A pellicle is a proteinous protective layer that covers the membrane of most protists. This structure confers rigidity upon the organism that possesses it and also gives it shape. The PELLICLE is responsible for the definite shape of the paramecium. The shapelessness and flexibility of the amoeba is due to the absence of PELLICLE that surrounds its membrane.