Ergotism is due to consumption of

Ergotism is a poisoning caused by ingestion of cereal grains (classically rye) that are infected by the fungus Claviceps purpurea; the fungus replaces kernels with toxic sclerotia that contain ergot alkaloids, and contaminated grain products (for example, rye bread) have historically caused outbreaks known as “St. Anthony’s fire” [1]. Reports and reviews consistently identify ergot-contaminated grains as the source of human and animal cases, and regulatory limits on ergot in cereals reflect its food-safety risk [2]. Therefore, among the options given, consumption of contaminated grains is the established cause of ergotism.

Sources

1. [1] https://asm.org/articles/2018/november/from-poisoning-to-pharmacy-a-tale-of-two-ergots
2. [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC6640538/