GMAT Sentence Correction (SC) | Re: Recently documented examples of neurogenesis, the production

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

A. the brain growing in mice when placed in a stimulating environment or neurons increasing in canaries that

Seems like the 'brain' is being disembodied and placed in a stimulating environment.

B. mice whose brains grow when they are placed in a stimulating environment or canaries whose neurons increase when they