Please help I’ve been stuck on this for so long :(

As a small change in a person's dna can cause a genetic disorder

All individuals have two alleles for a given trait. according to mendel's these alleles are passed down one each from both mother and father.

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures