Concept:Maize rust is a plant disease caused by a microscopic organism from the fungal group, not by animals or bacteria.
Explanation:Maize rust is a common disease of maize plants.
The disease mainly affects the leaves, producing reddish-brown pustules or rust-like spots.
These pustules contain spores of the causal organism.
The causative organism is a fungus scientifically known as
Puccinia sorghi.
Fungi are the pathogens responsible for most rust diseases in plants.
Nematodes, insects, and bacteria cause different diseases, but they are not the cause of maize rust.
Therefore, among the given options, the causative organism belongs to the group called fungus.
Answer:D. Fungus