Final answer:
Fungi obtain nutrients through 'b. absorption'. They use mycelia for efficient nutrient uptake, relying on external digestion by exoenzymes, which is unlike photosynthesis in plants or ingestion in animals.
Step-by-step explanation:
Fungi absorb nutrients from the environment through their mycelia. The structure of fungal hyphae is optimized for absorption due to a high surface-area-to-volume ratio. These absorption capabilities are further enhanced by the release of exoenzymes, allowing fungi to externally digest nutrients such as polysaccharides, proteins, and lipids and then absorb the smaller resulting molecules.
The correct answer to the student's question is 'b. absorption.' Unlike plants that use photosynthesis and certain bacteria that rely on chemosynthesis, fungi do not produce their nutrients. They also differ from animals, which typically use endocytosis and ingestion for nutrient uptake. Thus, fungi's digestive process is external, followed by the absorption of nutrients, which aligns with their heterotrophic nature.