GMAT Sentence Correction (SC) | Present tense and present perfect - impossible?

Hi there

I do have a particular question re the use of tenses on one question explanation: (OG 2017,#219):

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

D) Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood,

OA re D
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