What are some ways another kind of natural disaster could change an environment and change the selective pressures felt by a species?

Attached earlobes are a reccesive trait in humans. in the tree below, people with attached earlobes are shaded in. which best describes labeled x in the tree? a: a female with one recessive allele b: a female with no recessive allelesc: a male with no recessive allelesd: a male with one recessive allele