Which disease is specifically known for creating galls on ornamental plants?

The correct choice is the one that specifically identifies the disease known for creating galls on ornamental plants. Galls are abnormal growths that occur primarily as a response to various biotic agents, including certain pathogens and insects.

In the context of ornamental plants, galls are commonly induced by specific diseases such as those caused by certain types of fungi, bacteria, or even insects like gall wasps. The formation of galls can lead to distorted plant growth and may affect the overall health of the plant.

The other options refer to different types of diseases or conditions, such as leaf spots, which are typically characterized by discolored areas on foliage; Botrytis, which is more associated with blight and mold; and scab, which refers to unsightly lesions primarily on fruit or leaves. None of these options are associated with gall formation in the same specific manner as galls are, which directly points to the distinguishing feature of the correct answer.