The answer is letter a. loop
A planarian can regrow any missing body part. Truth be told, in the event that you take a planarian and excise it into a few little pieces, every last one of those body sections can recover into an entirely different worm.
Really really really small
The best answer is "foreshocks before the quake and aftershocks after the quake".
These terms are used to characterise the events of an earthquake over time. Foreshocks are small shocks that can occur before the main seismic event. Aftershocks, like foreshocks, are smaller seismic events that can occur after the main seismic event.
