Concept:The structure labelled III is a rhizoid, a root-like hypha of a fungus such as
Rhizopus, used for anchorage and external digestion.
Explanation:Rhizoids grow into the substrate and secrete digestive enzymes to break down organic matter.
These enzymes are released outside the fungal body, so digestion occurs externally before absorption.
Rhizoids are not true roots, so they do not absorb mineral salts mainly or form root hairs.
They anchor the fungus but do not develop into stolons.
Answer:Option A — secretes digestive enzymes into the substrate.
