How many events does the BaseFieldType provide?

Answer: Option C

BaseFieldType provides three events that you can latch code onto:
1. onBeforeSave() : Called right before a field is saved.
2. onAfterSave() : Called right after a field is saved, and $this->model->id is set.
3. onAfterElementSave() : Called right after an element is saved, and $this->element->id is set.