Final answer:
Fungi are characterized by the presence of chitin in their cell walls, hyphal growth forming a mycelium, and their heterotrophic mode of nutrition, distinguishing them from plants.
Step-by-step explanation:
Fungi have some unique characteristics that set them apart from other groups of organisms. Specifically, what sets them apart from plants is B) Presence of chitin in cell walls. Unlike plant cells that have cell walls made of cellulose, fungal cells have cell walls that contain chitin, a tough carbohydrate also found in the exoskeleton of arthropods. In addition, fungi exhibit hyphal growth, through thread-like structures called hyphae, which can collect into a mass called a mycelium. This is distinct in comparison to plant growth patterns. Furthermore, fungi are heterotrophic, meaning they absorb nutrients from their environment rather than photosynthesizing their own food like plants do.