The process during which a pre-existing cell splits to form two cells is called

This process is called cell division, primarily consisting of mitosis, or meiosis in the case of reproductive cells. In this process, the DNA is replicated, divided into two complete and identical groups of chromosomes. Both grooups are transferred to opposite ends of the cell, and the cell splits in half to form two new identical cells. 

Hair follicles, blood, etc.

The answer is b. increased blood flow reduces nerve sensitivity