What is the name of each labeled part?

The influenza virus cause the flu, but not other diseases. why?

How does the molecular clock work? a. it analyzes the brain functionality of two different species.b. it examines and compares the physical characteristics of two different species.c. it illustrates relationships between two different species.d. it compares the number of mutations that exist in the dna of two different species.

What field of science did harry hess study?