Genetic Testing of an Embryo Is Available to Couples Who

Multiple Choice

Genetic testing of an embryo is available to couples who want to avoid passing on a genetic defect to their offspring.One method of testing involves removing a single blastomere from an 8-cell stage embryo and analyzing it to determine if it carries the mutant gene.If no mutation is found,the now 7-cell embryo can be implanted in the woman,and it can go on to develop into a healthy infant.These results indicate that

A) at least one of the cells in the human embryo at the 8-cell stage is not used in development.
B) the embryo can compensate for the loss of a cell.
C) not all cells are equally important.
D) the human embryo at the 8-cell stage has not yet formed an inner-cell mass.
E) the cell that is removed for testing is derived from the trophoblast.