An organism which exhibit extracellular digestion is

Step 1: Analyze the question We need the organism that digests food outside its cells (extracellular digestion), usually by secreting enzymes onto the food and then absorbing the digested products.

Step 2: Explain the concept

• Intracellular digestion: food is taken inside the cell (e.g. in a food vacuole) and digested there. Examples: Amoeba, Paramecium.
• Extracellular digestion: enzymes are released outside the body or cell, and the digested nutrients are then absorbed. Examples: fungi such as Rhizopus (bread mould), Mucor, and mushrooms.

Step 3: Check each option

• A. Spirogyra: a green alga. It makes its own food by photosynthesis, so it does not digest food externally.
• B. Paramecium: a ciliate protozoan. It ingests food through the oral groove into food vacuoles, so digestion is intracellular.
• C. Amoeba: it engulfs food by phagocytosis using pseudopodia and digests it in a food vacuole. This is also intracellular.
• D. Rhizopus: a saprophytic fungus. Its hyphae secrete digestive enzymes onto the bread or decaying matter, and it then absorbs the soluble products. This is extracellular digestion.

Step 4: Answer The correct option is D. Rhizopus.

Tip: Think "fungi = fluids outside." Fungi (Rhizopus, Mucor, yeast, mushrooms) digest outside their bodies, while protozoans like Amoeba and Paramecium digest inside food vacuoles.