Flagella are long, thread-like appendages which provide some live single cells with the ability to move, motility. Bacteria which have flagella are either rod or spiral-shaped and are known as bacilli and spirochetes, respectively. Cocci, or round bacteria, are almost all nonmotile. I hope this helps you :) I Have this in my Bio Notes
The correct answer is B) chance
Allele frequencies in a gene pool change completely due to chance.