Answer:
The most appropriate reason for the presence of genetic diversity among siblings would be an option A. Â
Crossing over is an event that place during pachytene stage of prophase I. During this event, the genetic material is exchanged between the non-sister chromatids of homologous chromosomes.
It results in the production of a new combination of alleles in gametes. These combinations can be different from either parent.
So, when genetically varied gametes fused to form a zygote, it results in the development of genetic variation among population including siblings.