Recently documented examples of neurogenesis, the production of new brain cells, include the brain growing in mice when placed in a stimulating environment or neurons increasing in canaries that learn new songs.

A. the brain growing in mice when placed in a stimulating environment or neurons increasing in canaries that
B. mice whose brains grow when they are placed in a stimulating environment or canaries whose neurons increase when they
C. mice's brains that grow when they are placed in a stimulating environment or canaries' neurons that increase when they
D. the brain growth in mice when placed in a stimulating environment or the increase in canaries' neurons when they
E. brain growth in mice that are placed in a stimulating environment or an increase in neurons in canaries that

OA is E.

Although there are other errors (parallelism, pronouns, etc.) in the wrong choices, I would like to focus in the following:
In choices A and E (the OA), is there an important difference in meaning between "the brain growing" and "brain growth" in the context of the sentence?, In the same sense, is there an important difference in meaning between "neurons increasing" and "an increase in neurons"?

What's wrong with B? I know that sounds awkward to mention "mice" or "canaries" as examples of neurogenesis. But I don't think it is enough reason to eliminate them.

Despite my comments above, I agree that the OA is E. It is the best in comparison with the rest.