Answer:
a. Centromere
A centromere is a specialised DNA sequence of a chromosome that links pair of sister chromarids (a dyad)
Two other patterns of inheritance include natural eye color and hair color.
A pedigree is a symbolic diagram that is used to show the presence and presentation of specific alleles in the families of both parents. This is used mostly for genetically controlled diseases and conditions. If a couple is in genetic counseling a pedigree is valuable in helping to determine the risk of that couple having a child that will either present with the condition or be a carrier for the condition. A pedigree is also composed in a way, with shapes and colors, that is an easy to understand visual representation of the inheritance patterns.
It should be natural selection since there is no external influence implied. (like environment or genetic mutations.)
