Gibberellins were named after a fungus known as

The correct option is Gibberella fujikuroi.

Gibberellins are a class of plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, and leaf and fruit senescence.

These hormones were first discovered and isolated in Japan during the 1920s by scientists studying the "bakanae" (foolish seedling) disease in rice crops. This disease, which causes rice plants to grow excessively tall and spindly, leading to their collapse, was found to be caused by a pathogenic fungus.

The fungus responsible for producing the active compound that stimulated this abnormal growth was identified as the ascomycete fungus Gibberella fujikuroi (anamorph: Fusarium fujikuroi). As a result of this discovery, the active chemical substances isolated from the fungus were named "gibberellins" after the genus of the fungus, Gibberella.