I think the scientist distinguish whether an entity is living or non living be describing the single unit of life, the live cell that could multiply, reproduce and generate trough time also through ages. I hope you are satisfied with my answer and feel free to ask for more
The genetics of red hair appear to be associated with the melanocortin-1 receptor (MC1R), which is found on chromosome 16. Eighty percent of redheads have an MC1R gene variant.
I cannot find this source for this I'm sorry. I meant to add it but I lost the site
C. Vestigial structure is the correct answer