Answer:
Step-by-step explanation:
a) It is rather rare, having survived tens of thousands of years to reach us
b) it is endangered, discovery and exposure to visitors and outside air cause problems that threaten the very existence of those paintings.
c) It has a kind of perfection, as it has been ascertained that all those paintings were done in one try, without the artist hesitating or trying to correct anything, and yet, it is and Advanced kind of artwork, where we lack the more primitive trials or samples of the works of apprentices.