GMAT Critical Reasoning (CR) | Re: Yeasts capable of leavening bread are widespread

Yeasts capable of leavening bread are widespread, and in the many centuries during which the
ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into
bread doughs accidentally. The Egyptians, however, did not discover leavened bread until about
3000 B.C. That discovery roughly coincided with the introduction of a wheat variety that was
preferable to previous varieties because its edible kernel could be removed from the husk without
first toasting the grain.

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