Pollution is always a good way to go but you don't have to do air pollution you can do water pollution or both air and water pollution.
B: A mutation in one of G5W's parents, during gamete formation, created an X-linked dominant disease allele.
You need to analyze the sex gametes.
Boys are XY
Girls are XX
If you have an X-linked dominant disease you need only one affected X gamete to have the disease.
The mother has XX' where X' is de affected and reproduce with a healthy man XY and breed unhealthy boys, but because of the heterozygous gametes you could also have healthy ones XX and XY
