11. What is the source of the extra chromosome 21 in an individual with Down syndrome?
(A) Deletion in either parent
(B) Inversion in either parent
(C) Point mutation of the chromosome
(D) Nondisjunction in either parent
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統計: A(0), B(0), C(0), D(2), E(0) #3222888
統計: A(0), B(0), C(0), D(2), E(0) #3222888