Answer:
C: It has all been discovered by now.
Explanation:
There is still history out there that yet hasn't been discovered. So coming to this, humans have not found everything yet there is about our past, and past cultures. Such as tools, clothing, and much more.
It is an undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.