While studying the genetic makeup of corn, a new class of mutant genes was discovered by Barbara McClintock, a discovery which led to greater understanding of cell differentiation.
                    
                
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                Aa new class of mutant genes was discovered by Barbara McClintock, a discovery which led
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                Ba new class of mutant genes in corn were discovered by Barbara McClintock, leading
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                CBarbara McClintock discovered a new class of mutant genes, and it led
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                DBarbara McClintock discovered a new class of mutant genes, a discovery that led
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                EBarbara McClintock, who discovered a new class of mutant genes, leading
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