Loose smut is

Answer: Option A

Loose smut is internally seed borne.
Loose smut of barley is caused by Ustilago nuda. It is a disease that can destroy a large proportion of a barley crop. Loose smut replaces grain heads with smut, or masses of spores that infect the open flowers of healthy plants and grow into the seed.
The major symptom of loose smut is the "smutted" grain heads, which contain masses of black or brown spores.
The most widely used method of control for loose smut is using treated seed. Seeds are typically treated with a systemic fungicide to kill any fungus that may be inside.