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【单选题】Defective Genes and Human Health Each of us carries about half a dozen defective(有缺点的) genes. We remain blissfully(快乐地) unaware of this fact unless we, or one of our close relatives, are amongst the m...
A.
Genetically engineered proteins are better than blood products in treating hemophilia.
B.
Only those who suffer from a genetic disease carry about half a dozen defective genes.
C.
The Y chromosome males have are from their fathers.
D.
Whether a defensive gene produces ill effects has something to do with the environment in which the gene operates.