The nonmutant allele of the brca1 gene to suppress tumor formation in women who are heterozygous for the mutation. women heterozygous for brca1 nevertheless have a 50% to 70% chance of developing breast cancer before age 70, and the usual reason is that the nonmutant allele is lost or inactivated in a lineage of cells. one possible mechanism for such "loss of heterozygosity" is:
a. germ cells in the affected individual develop a mutation in the nonmutant allele of brcal.
b. a somatic mutation in a breast cell inactivates the nonmutant brca1 allele.
c. a silent mutation occurs in the nonmutant brca1 allele.

Option B

Explanation:

A silent mutation has no effect on the gene activity and function hence option C is incorrect. Germ cells would affect the gametes produced, not the body's proteins hence the answer would be B.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.