Please Use the Following Information to Answer the Question(s)below

Multiple Choice

Please use the following information to answer the question(s) below.
In Figure 24.1,data are presented from an eight-year experiment in which 12 populations of Escherichia coli,each begun from a single cell,were grown in low-glucose conditions for 20,000 generations.Each culture was introduced to fresh growth medium every 24 hours.Occasionally,samples were removed from the populations,and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E.coli population.
Figure 24.1
-If the vertical axis of Figure 24.1 refers to "Darwinian fitness," then which of the following is the most valid and accurate measure of fitness?

A) number of offspring or close kin that survive to reproductive age
B) amount of ATP generated per cell per unit time
C) average swimming speed of cells through the growth medium
D) amount of glucose synthesized per unit time
E) number of generations per unit time