Answer: a) copy tissue
Explanation:
Tissue and cells in general get damaged, or just break down from wear and tear. So the cells divide to make up for this shortcoming, effectively replacing any broken parts with fresh new ones.
A mole of a substance is defined as: The mass of substance containing the same number of fundamental units as there are atoms in exactly 12.000g of 12C. Fundamental units change depending on the substance.
