The Following Questions Refer to the Information Below -Which of These Items Does Not Necessarily Exist in a Compared

The following questions refer to the information below.
A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals with the homologous human gene. The sequence homology between each species' version of the gene and the human gene is presented as a percentage of similarity.
$$\begin{array} { l c } \text { Species } & \text { Percentage } \\\hline \text { Chimpanzee } & 99.7 \\\text { Orangutan } & 98.6 \\\text { Baboon } & 97.2 \\\text { Rhesus Monkey } & 96.9 \\\text { Rabbit } & 93.7\end{array}$$

-Which of these items does not necessarily exist in a simple linear relationship with the number of gene-duplication events when placed as the label on the vertical axis of the graph below?

A) number of genes
B) number of DNA base pairs
C) genome size
D) mass (in picograms) of DNA
E) phenotypic complexity